Indian prime minister Manmohan Singh voiced "serious concerns" to David Cameron today over corruption allegations relating to the sale of Westland helicopters to his country's air force, as the two men met for talks in New Delhi.

Singh's decision to raise the issue in a joint press conference with Cameron cast a shadow over a trade mission designed by the British premier to promote a "special partnership" between the UK and India.

Cameron promised to provide any information requested by the Indian authorities, but stressed that the case was for Italian investigators to probe, as AgustaWestland is owned by Italian firm Finmeccanica.

India suspended payments under the £480 million contract following the arrest last week of Finmeccanica chairman and chief executive Giuseppe Orsi and AgustaWestland chief executive Bruno Spagnolini on corruption and tax fraud charges.

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Sitting alongside Cameron following their talks at Hyderabad House today, Singh said: "I... conveyed to the prime minister our very serious concerns regarding allegations about unethical means used in securing the 2010 contract for AgustaWestland helicopters.

"I told him that we have sought an explanation from the company by February 22 to examine if the contractual conditions on unethical practices and the integrity pact have been violated.

"I have sought full assistance from the UK in this case. prime minister David Cameron has assured me of the co-operation of his Government in the investigation."

Cameron said: "In terms of AgustaWestland, we will respond to any request for information. I am glad that the Italian authorities are looking into this issue in detail, as Finmeccanica is an Italian company."

Cameron said: "In Britain, we have introduced anti-bribery legislation that is probably the strongest anywhere in the world and we will root out any problems of bribery and corruption wherever and whenever they appear."

Singh pressed Cameron on the issue of visas for Indian nationals visiting the UK, which has caused concern among the business community and students.

The Indian PM stressed the importance of education, science and trade in enhancing relations between the two countries.

He said: "I impressed upon the prime minister the need for a visa regime that facilitates greater movement of people between the two countries."

Cameron has used his visit to launch a new same-day visa regime for Indian businesspeople, in response to unhappiness over previous arrangements which could see them waiting three days or more.

He has repeatedly said there is "no limit" on the number of Indians who can study at UK universities or take up graduate-level jobs after qualifying.

In today's talks, Singh and Cameron agreed closer co-operation between the UK and India over cyber-security, which is expected to see the establishment of a joint taskforce to share information on malicious IT attacks from criminal gangs, terrorists and state agents.

And they signed a memorandum of understanding on bilateral civil nuclear co-operation. India already has a civil nuclear energy programme, delivering 3% of the country's electricity, but over the next 10 years Delhi wants to increase its nuclear generation fivefold.

Today's agreement will facilitate the involvement of UK firms like Rolls-Royce in the development of India's nuclear capacity, by setting out arrangements for the transfer of sensitive technical information.

Both men stressed the importance of developing trade links between the UK and India. Cameron has a target of doubling bilateral trade by 2015, and today said he wanted the accelerating growth in economic links to extend beyond that date.

The PM said he wanted to see "rapid progress" towards the completion of an EU-India free trade agreement.

Both he and Singh agreed that their countries should be "inextricably linked" in future and wanted to see a "very special partnership" grow up between India and the UK, said Cameron.

"The potential of this relationship is immense and we are committed to working together to make sure we realise its full potential in every regard," he said.

Singh said: "David Cameron's personal commitment and leadership have imparted a strong momentum to the strategic partnership between India and the UK."

He said that today they expressed "satisfaction with progress in our economic engagement, while stressing the need to do more to take the relationship to a higher level".

Cameron said Britain and India were "on track" to double trade to £23 billion by 2015.

"We want to go further and open further British trading offices here in India," he added. "We want to create a pan-Indian network of British business centres by 2017.

"We want to make very rapid progress on the EU-India free trade agreement. I think there is a window of opportunity for all sides to look at what extra they can bring to completing a deal which could do as much as anything to help growth both here and in the EU.

"We discussed today how we should both be looking at how we reduce the barriers to investing in our countries."

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  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron (L) shakes hands with his Indian counterpart Manmohan Singh prior to a meeting in New Delhi on February 19, 2013. British Prime Minister David Cameron promised full cooperation with India and its police as a probe into alleged kickbacks in a helicopter deal clouded his meetings Tuesday with leaders in New Delhi. AFP PHOTO/ Prakash SINGH (Photo credit should read PRAKASH SINGH/AFP/Getty Images)

  • Prime Minister David Cameron Official Visit To India

    DELHI, INDIA - FEBRUARY 19: British Prime Minister David Cameron shakes hands with Indian Prime Minister Manmohan Singh at Hyderabad House on February 19, 2013 in New Delhi, India. British Prime Minister David Cameron arrived in India on Monday for an official three-day trip accompanied by a large business delegation from the UK. (Photo by Daniel Berehulak/Getty Images)

  • Prime Minister David Cameron Official Visit To India

    DELHI, INDIA - FEBRUARY 19: British Prime Minister David Cameron shakes hands with Indian Prime Minister Manmohan Singh at Hyderabad House on February 19, 2013 in New Delhi, India. British Prime Minister David Cameron arrived in India on Monday for an official three-day trip accompanied by a large business delegation from the UK. (Photo by Daniel Berehulak/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron (L) shakes hands with his Indian counterpart Manmohan Singh prior to a meeting in New Delhi on February 19, 2013. British Prime Minister David Cameron promised full cooperation with India and its police as a probe into alleged kickbacks in a helicopter deal clouded his meetings Tuesday with leaders in New Delhi. AFP PHOTO/ Prakash SINGH (Photo credit should read PRAKASH SINGH/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron (L) shakes hands with his Indian counterpart Manmohan Singh prior to a meeting in New Delhi on February 19, 2013. British Prime Minister David Cameron promised full cooperation with India and its police as a probe into alleged kickbacks in a helicopter deal clouded his meetings Tuesday with leaders in New Delhi. AFP PHOTO/ Prakash SINGH (Photo credit should read PRAKASH SINGH/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron (L) shakes hands with his Indian counterpart Manmohan Singh prior to a meeting in New Delhi on February 19, 2013. British Prime Minister David Cameron promised full cooperation with India and its police as a probe into alleged kickbacks in a helicopter deal clouded his meetings Tuesday with leaders in New Delhi. AFP PHOTO/ Prakash SINGH (Photo credit should read PRAKASH SINGH/AFP/Getty Images)

  • Cameron visit to India - Day 1

    Prime Minister David Cameron attends a reception at the Museum of Mumbai for Indian and British businessmen and women and hosted by the CEO of BP Bob Dudley (right) and Mukesh Ambani (left) of the Indian firm Reliance and the richest man in India. PRESS ASSOCIATION Monday February 16 2013. Mr Cameron is on a three day trade visit to India where he will later hold talks with his Indian counterpart Dr Manmohan Singh in Delhi. See PA story POLITICS Cameron. Photo credit should read: Stefan Rousseau/PA Wire

  • Cameron visit to India - Day 1

    Prime Minister David Cameron poses with Indian boys who he played cricket with at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron attends a reception at the Museum of Mumbai for Indian and British businessmen and women and hosted by the CEO of BP Bob Dudley (right) and Mukesh Ambani (left) of the Indian firm Reliance and the richest man in India. PRESS ASSOCIATION Monday February 16 2013. Mr Cameron is on a three day trade visit to India where he will later hold talks with his Indian counterpart Dr Manmohan Singh in Delhi. See PA story POLITICS Cameron. Photo credit should read: Stefan Rousseau/PA Wire

  • Cameron visit to India - Day 1

    Prime Minister David Cameron attends a reception at the Museum of Mumbai for Indian and British businessmen and women and hosted by the CEO of BP Bob Dudley. PRESS ASSOCIATION Monday February 16 2013. Mr Cameron is on a three day trade visit to India where he will later hold talks with his Indian counterpart Dr Manmohan Singh in Delhi. See PA story POLITICS Cameron. Photo credit should read: Stefan Rousseau/PA Wire

  • Cameron visit to India - Day 1

    Prime Minister David Cameron plays cricket with Indian boys at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron attends a reception at the Museum of Mumbai for Indian and British businessmen and women and hosted by the CEO of BP Bob Dudley. PRESS ASSOCIATION Monday February 16 2013. Mr Cameron is on a three day trade visit to India where he will later hold talks with his Indian counterpart Dr Manmohan Singh in Delhi. See PA story POLITICS Cameron. Photo credit should read: Stefan Rousseau/PA Wire

  • Cameron visit to India - Day 1

    Prime Minister David Cameron plays cricket with Indian boys at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron plays cricket with Indian boys at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron plays cricket with Indian boys at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron plays cricket with Indian boys at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron plays cricket with Indian boys at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron plays cricket with Indian boys at the Oval Maidan, a communal cricket pitch in the centre of Mumbai, India.

  • David Cameron

    British Prime Minister David Cameron, center, arrives to pay tribute at the Police Memorial in Mumbai, India, Monday, Feb. 18, 2013. Cameron called on India to further open up to foreign investment and loosen regulations that hamper businesses, saying Monday that the countries' "special relationship" could blossom into a powerful economic partnership. (AP Photo/Rajanish Kakade)

  • Cameron visit to India - Day 1

    Prime Minister David Cameron arrives to lay a wreath at the memorial to commemorate the policemen who were killed in the terrorist attacks of November 2008, in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron lays a wreath at the memorial to commemorate the policemen who were killed in the terrorist attacks of November 2008, in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron arrives to lay a wreath at the memorial to commemorate the policemen who were killed in the terrorist attacks of November 2008, in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron lays a wreath at the memorial to commemorate the policemen who were killed in the terrorist attacks of November 2008, in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron arrives to lay a wreath at the memorial to commemorate the policemen who were killed in the terrorist attacks of November 2008, in Mumbai, India.

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron arrives to pay his respects at a memorial for fallen police and uniformed personnel who lost their lives in the 2008 terror attacks in Mumbai on February 18, 2013. British Prime Minister David Cameron arrived in India with what he called Britain's biggest ever overseas business delegation for a three-day visit clouded by a corruption scandal.. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron arrives to pay his respects at a memorial for police and uniformed personnel who lost their lives in the 2008 terror attacks in Mumbai on February 18, 2013. British Prime Minister David Cameron arrived in India with what he called Britain's biggest ever overseas business delegation for a three-day visit clouded by a corruption scandal. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • INDIA-BRITAIN-DIPLOMACY-ECONOMY

    British Prime Minister David Cameron speaks during a business seminar in Mumbai on February 18, 2013. Cameron arrived in India's financial hub Mumbai on a three-day trade-focused visit clouded by a corruption scandal over British-made helicopters sold to New Delhi. AFP PHOTO/Indranil MUKHERJEE (Photo credit should read INDRANIL MUKHERJEE/AFP/Getty Images)

  • Cameron visit to India - Day 1

    Prime Minister David Cameron arrives in Mumbai, India ahead of his three-day visit to the country.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron holds a Q&A session with Unilever employees at their headquarters in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron holds a Q&A session with Unilever employees at their headquarters in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron holds a Q&A session with Unilever employees at their headquarters in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron holds a Q&A session with Unilever employees at their headquarters in Mumbai, India.

  • Cameron visit to India - Day 1

    Prime Minister David Cameron arrives in Mumbai, India ahead of his three-day visit to the country.