21/08/2013 10:18 BST

David Miranda's Detention Under Anti-Terror Laws Was 'Right', Says Theresa May

Britain's Home Secretary Theresa May leaves 10 Downing Street in London, Thursday, May 23, 2013. The British government's emergency committee met Thursday after two attackers butchered a British soldier in a daylight attack in London that raised fears terrorism had returned to the capital. Prime Minister David Cameron says there are strong indications it was an act of terrorism, and his top advisers will be examining the potential security implications of the attack, which took place near a military barracks in the Woolwich area of the city. Police Thursday confirmed the dead man was a serving soldier and said his identity will not be released yet at his family's request. They said a post-mortem examination will be conducted later Thursday.(AP Photo/Alastair Grant)

Theresa May has defended the use of anti-terror laws to detain the partner of the Guardian journalist behind a series of stories exposing the activities of American and British intelligence agencies.

On Sunday David Miranda, the partner of Glenn Greenwald, was held by police for nine hours at Heathrow airport and had several personal items confiscated.

Speaking on BBC Radio 4's World at One programme on Wednesday, the home secretary said she believed "it is right" that the police be able to use the controversial Schedule 7 of the Terrorism Act 200 to detain people if they believe they were in possession of information "that could be a danger to an national security or could be of a help to terrorists".

"It is absolutely right that if the police believe that somebody has in their possession highly sensitive stolen information that could help terrorists and could lead to a loss of lives its right that the police should act. Schedule 7 of this Act enables the police to act, it gives them the framework to do that," she said.

And she indicated the government would not make further changes to Schedule 7 to safeguard the rights of those detained.

"I believe that the proposals that we have put forward [to make changes] have addressed the issues that have previously been raised," she said.

May also defended David Cameron's decision to instruct cabinet secretary Sir Jeremy Heywood to put pressure on The Guardian to destroy hard disks that contained information obtained from NS whistle-blower Edward Snowden.

However speaking to the same programme, Lord Falconer, the former Labour cabinet minister who helped introduce the Terrorism Act 2000, said May's justification for its use in this case did not appear to stand up to scrutiny as Miranda was clearly not a terrorist.

He said the now infamous Schedule 7 of the Act was intended for use to "determine whether someone is a terrorist". Lord Falconer added: "if you know they are not a terrorist you cant use these powers."

"The justification given by the home secretary doesn't look right. Using a power to determine whether someone is a terrorist when you know they are not, is not the way to deal with that. There are other power which have protection for the citizen that could have been used instead," he said.

On Sunday Miranda was held by police at Heathrow Airport for nine hours as he changed planes on a journey from Berlin to his home in Brazil. Scotland Yard and the Home Office have insisted the actions of officers at the airport were proper.

Miranda claimed agents questioned him about his "entire life" and took his "computer, video game, mobile phone, my memory card - everything".

Schedule 7 applies only at airports, ports and border areas, allowing officers to stop, search, question and detain individuals.

Its use has been criticised by Greenwald - the reporter who interviewed Snowden - as a "profound attack on press freedoms and the news-gathering process", and has sparked concern on the use of terror laws.

Lawyers for Miranda have written to both May and Britain's most senior police officer challenging the legality of the decision to detain him for nine hours using Schedule 7.

Earlier today Nick Clegg confirmed he had agreed to Cameron's request that the cabinet secretary,put pressure on The Guardian to destroy data it received from Edward Snowden - which the paper eventually agreed to do under supervision of agents from GCHQ.

"On the specific issue of records held by The Guardian, the deputy prime minister thought it was reasonable for the Cabinet Secretary to request that the Guardian destroyed data that would represent a serious threat to national security if it was to fall into the wrong hands," the Lib Dem leader's spokesperson said.

May told the BBC: "Issues of national security are rightly addressed at an appropriate level within government. I do not find it surprising somebody at a very senior level within government should be involved in this particular issue.

"I think it is right and proper the government had those discussions with the Guardian, that the action that was taken was taken.

"If government believes information that could be of help to terrorists is potentially being held insecurely, could fall into the wrong hands, I think it is right the government should act. I don't find it strange that should be done at a senior level."

May was backed up by foreign secretary William Hague said: "The government clearly has a duty if information is held insecurely and could be damaging to our national security to try to make sure that it is recovered or destroyed. It's a very simple matter."

On Tuesday the White House distanced itself from the British government's decision to put pressure on The Guardian to destroy its files.

Asked by reporters whether the Obama administration would take similar action in the US, White House deputy press secretary Josh Earnest said: "It's very difficult to imagine a scenario in which that would be appropriate."

Labour's Keith Vaz, chairman of the Home Affairs Select Committee, called on Cameron to make a "full statement" to Parliament on the day it returns after the summer break to explain his actions.

He said: "The actions of the cabinet secretary are unprecedented and show that this issue has reached the highest levels of government.

"Although I am very surprised at this revelation, it explains why Downing Street, the White House and the Home Secretary were briefed in advance about David Miranda's detention."