Two weeks after he allegedly came within a hairsbreadth of bringing down Northwest Airlines Flight 253 from Amsterdam, 23-year-old Nigerian Umar Farouk Abdulmutallab, has pleaded not guilty after hearing charges against him in a federal courthouse in downtown Detroit.

It was his first formal court appearance.

Held since Christmas Day in federal detention, Abulmuttallab is being represented by Miriam Siefer, a highly respected lawyer who heads the office of public defenders in Detroit. Her options going forward seemed limited however, given the circumstances of the alleged terror attack. The suspect was tackled by crew and passengers after flames shot from his clothes as the plane began its approach to Detroit airport.

Some observers in Michigan played down the possibility that the defence might eventually seek a plea bargain in exchange for his providing information on how his mission was planned. US officials have already indicated that he has volunteered information that he was assisted by an affiliate of al Qaeda in Yemen.

A grand jury delivered six charges against Abdulmutallab this week, the most serious of which was trying to bring down an airliner with a weapon of mass destruction which is punishable by a life sentence in prison.

"A person who wants to blow himself up in an airplane over Detroit is not looking to shave some time off in the big house," said Lloyd Meyer, a former terrorism prosecutor at the Guantanamo Bay prison.