Abdulmutallab, who was overpowered by passengers and crew of Northwest flight 253, was taken into custody after the jet landed safely in Detroit.
He suffered extensive third-degree burns and two passengers were slightly injured.
Officials said Abdulmutallab tried to detonate an explosive device, apparently a mix of powder and liquid, as the flight, coming from Nigeria via Amsterdam, was approaching Detroit.
Peter King, the senior Republican on the House of Representatives Homeland Security Committee, told Fox News channel: “When it did go off, he himself was seriously injured. He has third-degree burns.”
'Terrorist connection'
He told CNN that Abdulmutallab, 23, “did appear in a database as far as having a terrorist connection”.
“My understanding is … that he does have al-Qaeda connections, certainly extremist terrorist connections, and his name popped up pretty quickly” in a search of intelligence data bases.
Citing unnamed officials, the Wall Street Journal said the suspect had told investigators al-Qaeda operatives in Yemen had given him the device and instructions on how to detonate it.
But NBC television, citing counterterrorism officials, said he “claims to have been acting on his own.”
A senior Homeland Security official, quoted by the New York Times, said the device “was made from a mixture of powder and liquid” and was “more incendiary than explosive.”
The official said Abdulmutallab told authorities he had explosive powder taped to his leg and used a syringe filled with chemicals to mix with the powder in an attempt to cause an explosion.
The flight was carrying 278 people and 11 crew members. The incident unfolded around noon local time (17:00 GMT).
Measures enforced
Homeland Security said enhanced security measures had been put into effect after the failed attack.
“Passengers may notice additional screening measures put into place to ensure
the safety of the travelling public on domestic and international flights,” it said in a statement.
President Barack Obama, who is currently on holiday in Hawaii, was “actively monitoring” the situation, a White House spokesman said.
“The president was notified of the incident this morning between 9am (07:00 GMT) and 9.30am Hawaii time by the president's military aide,” Bill Burton said in a statement.
After Obama was informed of the incident he held a secure conference call with John Brennan, his homeland security and counterterrorism adviser, and Denis McDonough, the National Security Council chief of staff .
“[Obama] asked to arrange a subsequent secure call and… instructed that all appropriate measures be taken to increase security for air travel,” the White House said.
'Explosion attempt' on US flight
