An Al Qaeda suicide bomber dispatched from Yemen to down a passenger plane with military-grade explosives was actually a double-agent recruited by foreign intelligence services, reports have claimed.
The bomber, who has not been named, was sent by the Yemen branch of the terrorist group to blow up a jet bound for the United States via the United Arab Emirates.
The bomb, which was "undetectable" and contained no metal, had two detonators and was sewn into customised underwear. The Daily Mail said it was a more advanced version of a device with which bombers attempted to destroy a plane above Detroit on Christmas Day 2009.
The device would have "undoubtedly would have brought down an aircraft" according to an American official quoted in media reports.
The attack was reportedly scheduled to mark the first anniversary of the death of Al Qaeda leader Osama Bin Laden on 2 May.
But in what the New York Times has called an "extraordinary intelligence coup", the man was later revealed to in fact be working for the Saudi Arabian authorities and the CIA.
The London Times said that British officials were also involved, but added the security forces had declined to comment.
The bomber left Yemen last month before handing over the bomb, detailed plans for the attack and information on the leaders of the terrorist group, their locations and their future plots.
The information was not revealed to protect the agent and his family, officials have said.
According to the New York Times the bomb is now being analysed at its lab in Virginia to prevent future attacks and improve airport security.
The details provided by the agent led to a CIA-directed drone attack in Yemen which killed Yemeni Al Qaeda operations director Fahd Mohammed Ahmed Al-Quso, who was wanted for the bombing of the USS Cole in 2000.
Quso, who was 37, had a $5m bounty on his head according to CIA officials.
The American authorities said that they had been aware of the agent for several years, but that he was under the control of the Saudi government.
The story was first reported by the LA Times, apparently to the annoyance of American officials who claimed it might discourage governments from cooperating with the CIA in future.
Take a look at 10 other failed terrorist attempts, involving everything from shoe bombs to ricin, for another phew moment.
Scotland Yard
Richard Reid(01 of10)
Open Image ModalRichard Reid attempted to detonate a bomb in his shoes, months after September 11. While aboard American Airlines flight 63 from Paris to Miami on 22 December 2001 Reid attempted to ignite plastic explosives hidden in his shoes. He was overpowered by flight attendants and passengers, and admitted the charges in his 2002 trial. He was sentenced to life in prison. (credit:Getty)
New York Subway(02 of10)
Open Image ModalTwo men attempted to bomb New York's Subway system in August 2004, the day before the Republican National convention. Shahawar Matin Siraj and James Elshafay were both sentenced to 30 years in prison. (credit:Getty)
2006 transatlantic airline plot(03 of10)
Open Image ModalPolice foiled a plot to use liquid explosives on 10 planes travelling from the UK to Canada and the US, leading to continuing restrictions on passengers carrying liquids on planes. Deputy Commissioner of the Metropolitan Police, Paul Stephenson said the terrorists aimed at causing 'untold death and destruction and to 'commit mass murder on an unimaginable scale' (credit:Getty)
London car bombings(04 of10)
Open Image ModalTwo car bombs were discovered in central London in 2007, with both containing petrol cans, nails and gas canisters. They were designed to be trigged by a mobile device. The event was linked to a terrorist attack on Glasgow airport by Bilal Abdullah, and he was sentenced for conspiracy to murder for both accounts. (credit:Getty)
2007 plot to behead a British Muslim soldier (05 of10)
Open Image ModalOperation gamble investigated a plot to behead a British-Muslim solider in 2007. The seven month police investigation led Parviz Khan to be sentenced to prison for life. One associate was sentenced for supplying equipment to militants in Afghanistan.
Umar Farouk Abdulmutallab (06 of10)
Open Image ModalUmar Farouk Abdulmutallab was caught attempting to detonate a bomb hidden in his underpants on board a flight from Amsterdam to Detroit on Christmas Day in 2009. The former UCL student was sentenced to life in prison.
Bronx terrorism plot(07 of10)
Open Image ModalPolice arrested four men in 2009 after discovering a plot to blow up two synagogues. The so-called Bronx terrorism plot led to a terrorist ring, led by James Cromitie, being tried and convicted. (credit:PA)
2008 Exeter 'bomb'(08 of10)
Open Image Modal22 year old Muslim convert Nicky Reilly was the only person injured during a failed suicide attack at a restaurant in Exeter.
Attempted tube bombings, 2005(09 of10)
Open Image ModalAfter the panic of the 7 July London bombings on the tubes, another attempt was made to attack the capital two weeks later on 21 July 2005. Tune stations and lines were evacuated but the bombs failed. Each of the four attempted bombers were sentenced to a minimum of 40 years in prison.
'Ricin plot'(10 of10)
Open Image ModalAlgerian terrorist Kamel Bourgass was jailed for 17 years after police discovered equipment to produce poisons in his flat in 2003. In a statement the Met's Deputy Assistant Commissioner Clarke said: "The impact on the public, if he [Bourgass] had succeeded in what he wanted to do, is incalculable."