An explosive allegedly concealed in the underwear of a Nigerian student accused of trying to blow up a plane was powerful enough to put a hole in the side of an airliner, according to reports.
Media reports, quoting federal investigators, say that the bomb packet contained 80 grams of the explosive chemical PETN, sewn into the briefs of Umar Farouk Abdulmutallab.
Shoe bomber Richard C. Reid had carried 50 grams of the material in his thwarted attack in December 2001.
Officials have said that the detonator used by Abdulmutallab, a syringe filled with acid, failed to work, which averted an explosion.
Abdulmutallab is being held in a federal prison in Michigan after suffering burns in the alleged bombing attempt. He is accused of trying to ignite an explosive device on Northwest Airlines Flight 253 from Amsterdam on Friday.
Al-Qaeda in Arabian Peninsula, which is based in Saudi Arabia and Yemen, has claimed Abdulmutallab coordinated with members of the group and that the explosives he allegedly carried on the Northwest Airlines flight were made by al-Qaeda members.
U.S. authorities have also said he claimed to be carrying out an attack on orders from al-Qaeda.
The Washington Post said it has reviewed 300 online postings believed to be from the suspect under the name "farouk1986" — which is a combination of Abdulmutallab's middle name and birth year.
"I have no one to speak too [sic]," read a posting from January 2005, when Abdulmutallab was attending boarding school. "No one to consult, no one to support me and I feel depressed and lonely. I do not know what to do. And then I think this loneliness leads me to other problems."
He also wrote of his "dilemma between liberalism and extremism" as a Muslim.
"The Prophet (S) said religion is easy and anyone who tries to overburden themselves will find it hard and will not be able to continue," he wrote in 2005. "So anytime I relax, I deviate sometimes and then when I strive hard, I get tired of what I am doing i.e. memorising the quran, etc. How should one put the balance right?"
In Yemen, investigators tried to piece together the movements and contacts of Abdulmutallab, who had been in the country studying Arabic in the capital city of San'a.
The San'a Institute for the Arabic Language said Abdulmutallab was a student at the school in August, but questions remain what he did in the country between then and December.
The director of the school, Muhammad al-Anisi, remained in custody Tuesday, having been questioned for two days.
U.S. President Barack Obama said on Monday the government will use "every element" of its power to prevent attacks on U.S. soil in the wake of the bombing attempt.
The president said he has also ordered an examination of the watch list system, which is used to identify known and suspected terrorists, and how it can be strengthened.
The U.S. government has said that Abdulmutallab had been on a broad watch list that includes more than 500,000 names after his father alerted embassy officials in Nigeria in November about his son's extremist beliefs.
U.S. Homeland Security Secretary Janet Napolitano said there was not enough information to put him on a no-fly list, which contains the names of people deemed to be a threat to the security of aircraft or air travellers.
Obama said he has also ordered a review of airport screening procedures.