US President Barack Obama has for the first time publicly accused an offshoot of al-Qaeda for the alleged Christmas Day bomb plot to blow up a US plane, BBC reported.
He said it appeared Yemen-based al-Qaeda in the Arabian Peninsula had armed and trained the accused, 23-year-old Nigerian Umar Farouk Abdulmutallab.
The group admitted responsibility in a statement last week.
The mid-air drama aboard Northwest Flight 253 on 25 December has spawned a worldwide aviation security review.
In his weekly radio and video address posted on the White House website early on Saturday, Mr Obama said more details of the alleged plot were becoming clear.
"We know that [Abdulmutallab] travelled to Yemen, a country grappling with crushing poverty and deadly insurgencies," said Mr Obama, who is on holiday in Hawaii.
"It appears that he joined an affiliate of al-Qaeda, and that this group, al-Qaeda in the Arabian Peninsula, trained him, equipped him with those explosives and directed him to attack that plane headed for America."
US officials have not until now publicly accused al-Qaeda over the incident on Flight 253 from Amsterdam to Detroit.
Mr Abdulmutallab, now in US custody, is accused of trying to detonate explosives strapped to his body as the plane, with nearly 300 people on board, prepared to land.