CIA foils al–Qaeda underwear bomb plot

• Discovery made around the one-year anniversary of the killing of Osama bin Laden

• FBI examining latest device

• No immediate plans to change airport security

The underpants explosives, which were uncovered before an attack took place, contain no metal so would potentially evade detectors at border controls.

UK officials will be keen to determine what threat they pose to security at this summer’s London Olympics, including many events taking place in Scotland.

It is not yet clear whether new body scanners used in many airports would have detected it.

The device is an upgrade of the underwear bomb that failed to detonate aboard a jetliner over Detroit on Christmas 2009.

This new bomb was also designed to be used in a passenger’s underwear, but this time al-Qaeda developed a more refined detonation system.

Senator Dianne Feinstein, who heads the Senate Intelligence Committee, said today she had been briefed about an “undetectable” device that was “going to be on a US-bound airliner”.

There were no immediate plans to change security procedures at US airports.

The would-be suicide bomber, based in Yemen, had not yet picked a target or bought a plane ticket when the CIA stepped in and seized the bomb, officials said.

It was not immediately clear what happened to the alleged bomber.

The operation unfolded even as the White House and Department of Homeland Security assured the American public that they knew of no al Qaida plots against the US around the anniversary of bin Laden’s death. The operation was carried out over the past few weeks, officials said.

The White House did not explain those statements last night.