[Watch] US foils new ‘Al Qaeda’ underwear bomb plot

The plan, around the first anniversary of Osama bin Laden's killing by US forces, involved a sophisticated version of the device that failed to detonate on board a plane heading to Detroit on Christmas Day 2009, they added.

The CIA thwarted the latest plan by al Qaeda's branch in Yemen and the new device has been recovered.

The FBI is examining the bomb to see whether it could have passed through airport security and brought down an aircraft, officials said.

They said the device did not contain metal, which means it probably could have passed through an airport metal detector.

But it was not clear whether new body scanners used in many airports would have detected it.

The would-be suicide bomber was told to buy a ticket on the airliner of his choosing and decide the timing of the attack.

But he had not yet picked a target or bought his ticket when the CIA stepped in and seized the bomb, officials added.

It was not immediately clear what happened to him.

The officials, who spoke on the condition of anonymity, said no airline was ever at risk.

US President Barack Obama was first told about the latest plot in April and has received regular updates, said deputy National Security Council spokeswoman Caitlin Hayden.

The White House said the plot never posed any risk to the public.

An FBI statement said: "As a result of close co-operation with our security and intelligence partners overseas, an improvised explosive device (IED) designed to carry out a terrorist attack has been seized abroad.

"The FBI currently has possession of the IED and is conducting technical and forensics analysis on it.

"Initial exploitation indicates that the device is very similar to IEDs that have been used previously by al Qaeda in the Arabian Peninsula (AQAP) in attempted terrorist attacks, including against aircraft and for targeted assassinations.

"The device never presented a threat to public safety, and the US Government is working closely with international partners to address associated concerns with the device."

It is not clear who built the bomb, but, because of its sophistication and its similarity to the Detroit device, authorities suspected it was the work of Ibrahim Hassan al Asiri.

He constructed the first underwear bomb and two others that al Qaeda built into printer cartridges and shipped to the US on cargo planes in 2010.

In the Detroit incident, a bomb hidden in the underwear of Umar Farouk Abdulmutallab caused a fire but failed to explode on a Delta Airlines flight carrying 289 people.

Abdulmutallab was eventually overpowered by passengers and crew on the Northwest Airlines flight 253 from Amsterdam.

He was jailed for life in February this year.