Suspect: Al-Qaida gave him explosive

The 23-year-old Nigerian man who was charged on Saturday with trying to blow up a Detroit-bound Northwest Airlines jet on Christmas told investigators he obtained the explosive chemicals -- which were sewn into his underwear -- from a bomb expert in Yemen associated with Al-Qaida.

The case prompted a significant change to airline security worldwide. Some passengers traveling Saturday were told that new U.S. regulations required that they stay in their seats for the final hour before landing. Airlines also said passengers flying into the United States would be allowed only one carry-on item and could have nothing on their laps for the final hour of flight.

Authorities have not independently corroborated the Yemen connection claimed by the suspect, Umar Farouk Abdulmutallab, who was burned in his failed attempt to bring down the airliner. But the law enforcement official said the suspect's account was "plausible," adding, "I see no reason to discount it."

"This alleged attack on a U.S. airplane on Christmas Day shows that we must remain vigilant in the fight against terrorism at all times," Attorney General Eric Holder Jr. said. "Had this alleged plot to destroy an airplane been successful, scores of innocent people would have been killed or injured. We will continue to investigate this matter vigorously, and we will use all measures available to our government to ensure that anyone responsible for this attempted attack is brought to justice."

If true, the attack would follow the terrorist group's tendency to return to failed plots, such as attacking the World Trade Center towers twice, in 1993 and 2001, for example.

U.S. officials said Saturday that a preliminary FBI analysis found a bomb-making chemical called PETN in the device Abdulmutallab tried to detonate. That's the same material convicted Al-Qaida conspirator Richard Reid used when he tried to destroy a trans-Atlantic flight in December 2001 with hidden explosives in his shoes.

About six weeks ago, an investigative file was opened on Abdulmutallab after his father warned officials at the U.S. Embassy in Nigeria of his son's increasingly extremist religious views, a senior Obama administration official said Saturday.

The affidavit filed Saturday described the chaos on board Flight 253. According to the document, Abdulmutallab spent about 20 minutes in the bathroom before returning to his seat and complaining of an upset stomach.

"He pulled a blanket over himself. Passengers then heard popping noises similar to firecrackers, smelled an odor, and some observed Abdulmutallab's pants leg and the wall of the airplane on fire," the affidavit says. "Passengers and crew then subdued Abdulmutallab and used blankets and fire extinguishers to put out the flames."

The disclosure of the use of PETN raised questions over the effectiveness of aviation screening techniques, experts said. "I just can't believe it," one former U.S. government official and explosives expert said, expressing shock the material was not discovered.

PETN should be detectable by existing explosive trace detection equipment that takes swabs off of passengers or baggage, as well as newer whole-body imaging scanners that travelers walk through, two former U.S. government officials said.

U.S. sources also noted that the suspect's mode of attack -- detonating a few grams of PETN hidden on his body -- is similar to tactics used by another failed suicide bomber with known links to Al-Qaida's Yemeni branch. In August, Abdullah Hassan Tali Assiri tried to assassinate a member of Saudi Arabia's royal family using PETN explosives hidden inside his rectum, according to a published account by terrorism expert Peter Bergen.

Some airlines announced Saturday that passengers flying into the United States will be allowed only one carry-on item, will be restricted to their seat during the final hour of flight and will not have access to carry-on luggage during that hour, nor will they be able to have anything in their lap for that hour. The airlines, including British Airways and Air Canada, attributed the policy to U.S. security officials.

Canada, Belgium and France also began physically screening passengers and checked bags at boarding gates for flights bound for the United States, authorities said.

The Transportation Security Administration made no announcement on new policies, but Homeland Security Secretary Janet Napolitano said in a statement that travelers may notice additional unspecified security measures that could mean travel delays.

"These measures are designed to be unpredictable, so passengers should not expect to see the same thing everywhere," she said. "Both domestic and international travelers should allot extra time for check-in."

Abdulmutallab -- who is being treated for severe burns at the University of Michigan hospital in Ann Arbor -- is cooperating with law enforcement authorities, officials said. He was arraigned at the hospital's burn unit. According to reporters, he was asked how he was feeling and he responded: "I'm doing better."

Abdulmutallab grew up in a rarefied slice of Nigeria, the son of an affluent banker. He attended one of West Africa's best schools, the British School of Lome in Togo, and enrolled at the University College London to study engineering.

Investigators are examining how Abdulmutallab apparently rebelled against this privileged upbringing. In high school he began preaching to fellow students about Islam, according to ThisDay, a Nigerian newspaper.

ThisDay reported that more recently, Abdulmutallab had moved to the United Arab Emirates and told his family that he no longer wanted to associate with them.