of photos of the explosive device used by umar farouk abdulmutallab

Al Qaeda link called credible as clues emerge in foiled terror attack: Photos of the explosive device used by the Nigerian man to blow up a plane on Christmas Day has been released.

PETN

Part of an explosive device that failed to take down a plane last week was sewn into the underwear of the Nigerian man accused of igniting it, a law enforcement official told CNN Monday.

Umar Farouk AbdulMutallab is being held for allegedly trying to blow up a flight carrying 300 passengers on Christmas Day.

Al Qaeda in the Arabian Peninsula claimed responsibility Monday for the attack, saying it was in retaliation for alleged U.S. strikes on Yemeni soil.

In a message written in Arabic, dated Saturday and published Monday on radical Islamist Web sites, the group hailed the "brother" who carried out the "heroic attack."

The group said it tested a "new kind of explosives" in the attack, and hailed the fact that the explosives "passed through security."

Umar Farouk AbdulMutallab