Sources say Umar Farouk Abdulmutallab, 23, burnt his leg trying to ignite a small explosive device shortly before landing, but another passenger quickly helped subdue and isolate the young male suspect with support from crewmembers. Nobody else was seriously hurt.

The Nigerian suspect was placed in custody and is being treated for burns on his thighs. He told the police that he had been acting on behalf of al-Qaeda.

However, a senior administration official said there was no evidence that Abdulmatallab was a hard-core, trained member of al-Qaeda.

The incident is under investigation by the FBI. The remains of the used device are being sent to an FBI explosives lab in Quantico, Virginia, for analysis.