Underwear bomb plot foiled by CIA raid in Yemen

Updated version of 2009 device is seized as al-Qa'ida planned attack during flight

The CIA thwarted an al-Qa'ida plot to destroy a US-bound airliner close to the anniversary of Osama bin Laden's death using a bomb hidden in a terrorist's underwear, it was disclosed yesterday.

Agents seized the device in Yemen before it could be passed to the would-be suicide bomber, who had yet to pick a target or buy any tickets, according to US officials.

It is unclear what became of the intended bomber, but the weapon's sophisticated design has led to suspicions it was the work of the expert bomb-maker Ibrahim Hassan al-Asiri, considered by some US anti-terror experts to be the single most important security threat to the US.

An examination of the latest bomb by the FBI found that it contained no metal, potentially meaning it could have passed through airport scanners undetected. It was said to be a more refined version of the weapon with which Nigerian terrorist Umar Farouk Abdulmutallab tried to destroy an airliner carrying 300 passengers in 2009. He is now serving life in prison in the US.

Associated Press reported that it learned of the foiled plot last week but agreed to requests from the White House and CIA not to reveal it immediately because sensitive intelligence was still being gathered.

For President Barack Obama, the revelations may provide a political opportunity as he kicks off his re-election campaign to remind voters that under his watch no terror attack on the US has been successful, and that bin Laden is no longer alive.

Last night, White House spokeswoman Caitlin Hayden, said: "The President thanks all intelligence and counter-terrorism professionals involved for their outstanding work."

The fact that the device had no metallic parts will also help the US government justify the use at an increasing number of airports of body-imaging devices.

Leon Panetta, the US Defence Secretary, said last night that the administration "will do everything necessary to make America safe".

US officials meanwhile sought to emphasise last night that there was never any threat to the public because US CIA agents were aware of the plot virtually from its inception. "We were so on it, that's why we have the device," a White House source told CBS News.

Coming just a day after an American airstrike in Yemen killed Fahd al-Quso, a senior al-Qa'ida leader, the plot appears to underline the seriousness of the threat posed by terrorists working in the country. Large parts of Yemen are under control of Al-Qa'ida and other militants fighting against state forces, while the popular Arab Spring revolt against the now deposed President Ali Abdullah Saleh has added to uncertainty over the country's governance.