The underwear worn by terror suspect Umar Farouk Abdulmutallab on a Christmas flight from the Netherlands to Detroit contained the charred remains of the explosives he allegedly packed inside them in hopes of blowing up the airliner, authorities said.

Photographs of the briefs were revealed Monday night.

The bomb, seen for the first time, is reported to have contained a six-inch pack of highly-explosive powder called PETN, which weighed about 80 grams (less than 3 ounces) and was sewn into the briefs.

According to ABC News, a government test with 50 grams of PETN blew a hole in the side of an airliner — the same amount carried by so-called shoe bomber Richard Reid over Christmas in 2001.

A global search for accomplices in the Detroit airliner plot is under way after an Al Qaeda group based in Yemen claimed responsibility for the operation and the would-be bomber was reported to have said that more attacks were being planned.

Al Qaeda in the Arabian Peninsula, a terrorist cell led by a former personal secretary to Usama bin Laden, issued a statement saying that the failed attack by Umar Farouk Abdulmutallab was a response to American-backed airstrikes on the group in Yemen this month.

Yemeni government forces, acting on U.S. intelligence and using what officials have admitted was American military hardware, launched air raids on suspected militants in the east of the country on December 17 and again on December 24. At least 60 people were believed to have been killed.

Abdulmutallab, the 23-year-old Nigerian who set himself alight in a packed Northwest jet approaching Detroit on Christmas Day, bought his one-way ticket from a KLM office in Accra, the Ghanaian capital, on December 16, indicating that his attack was planned well before these latest air raids. A U.S. military effort to deny Al Qaeda a stronghold in Yemen has been under way for at least a year.

The fresh-faced engineering graduate was transferred yesterday from hospital in Detroit to a federal prison in Milan, Michigan, where agents questioning him said he told them that he was one of many bombers being groomed by the Yemeni Al Qaeda affiliate to attack American-bound aircraft, according to ABC News.

Yemeni authorities confirmed Monday that Abdulmutallab had been in the country since August.

The Times of London contributed to this report.