( CNN ) -- A Nigerian man accused of attempting to detonate an explosive device in his underwear aboard a flight to Detroit last Christmas pleaded not guilty Thursday to new charges , authorities said . Umar Farouk AbdulMutallab was indicted on two new counts -- conspiracy to commit an act of terrorism transcending national boundaries and possession of a firearm or destructive device in furtherance of an act of violence . He faces a maximum sentence of life in prison on the new charges and on six counts brought against him in early January if he 's convicted . During a 20-minute hearing Thursday , AbdulMutallab stood mute when asked his plea , so U.S. District Judge Nancy Edmunds entered a not guilty plea on his behalf , said Rod Hansen , court spokesman . `` The government asked for a trial date , but the judge said that because the superseding indictment had just been filed the day before , she wanted to give the defendant and his standby attorney time to look it over , '' Hansen said . A pretrial conference was set for January 12 . The initial charges against AbdulMutallab included attempted use of a weapon of mass destruction and willful attempt to destroy and wreck an aircraft within the jurisdiction of the United States . However , the first batch of charges did not include the specific word `` terrorism . '' AbdulMutallab entered a not guilty plea in January . In September , AbdulMutallab told Edmunds he did not want to be represented by the public defenders assigned to his case and would like to act as his own lawyer . Edmunds agreed but appointed a standby counsel for him in case he needs help . Asked on Thursday by Edmunds if he still wants to represent himself , a calm AbdulMutallab answered , `` Yes , ma'am , '' according to Hansen . The defendant was wearing a khaki-colored prison jumpsuit . He was handcuffed and shackled as he was led into court , but the cuffs and chains were removed before the judge entered . Also in September , AbdulMutallab asked Edmunds how to proceed if he would like to plead guilty to some charges . The judge told him that was something his standby lawyer could assist him with . AbdulMutallab was a passenger on Northwest Airlines Flight 253 en route from the Netherlands to Detroit on Christmas Day . According to the indictment , he went to the bathroom shortly before the plane was to land . When he returned to his seat he said his stomach was upset and he pulled a blanket over himself . Prosecutors allege he then tried to ignite an explosive device made of PETN and TATP that was hidden in his underwear . Passengers and flight crew members subdued him . U.S. officials say the terror group al Qaeda in the Arabian Peninsula was behind the alleged bombing attempt . CNN 's Susan Candiotti and Deb Feyerick contributed to this report .
AbdulMutallab pleaded not guilty to new charges . New weapons and explosives charges are pending against AbdulMutallab . He is accused of trying to set off an explosive device aboard a plane . The incident occurred on a plane flying into Afghanistan last Christmas .