A would-be "underwear bomber" involved in a plot to attack a US-based jet was in fact working as an undercover informer with Saudi intelligence and the CIA, it has emerged.
The revelation is the latest twist in an increasingly bizarre story about the disruption of an apparent attempt by al-Qaida to strike at a high-profile American target using a sophisticated device hidden in the clothing of an attacker.
The plot, which the White House said on Monday had involved the seizing of an underwear bomb by authorities in the Middle East sometime in the last 10 days, had caused alarm throughout the US.
It has also been linked to a suspected US drone strike in Yemen where two Yemeni members of al-Qaida were killed by a missile attack on their car on Sunday, one of them a senior militant, Fahd Mohammed Ahmed al-Quso.
But the news that the individual at the heart of the bomb plot was in fact an informer for US intelligence is likely to raise just as many questions as it answers.