DETROIT -

A federal appeals court has heard arguments in the case of a Nigerian man who tried to blow up a Detroit-bound jet on Christmas 2009.

An attorney for Umar Farouk Abdulmutallab says his guilty plea should be thrown out and a mental competency hearing ordered. Travis Rossman also argues that a life sentence for a young man is extreme, especially when no one except Abdulmutallab was seriously injured aboard Northwest Airlines Flight 253.

The 25-year-old called the bomb be carried in his underwear a “blessed weapon” to avenge poorly treated Muslims worldwide.

The bomb didn't fully detonate, but caused a brief fire that burned Abdulmutallab.

He admitted afterward that the attack was inspired by Anwar al-Awlaki, a radical American-born cleric and leading al-Qaida figure killed by a U.S. drone strike last fall.

An appeals court in Cincinnati heard arguments Thursday on those issues and more. There was no immediate decision.

Read: Underwear bomber appeals life sentences in airline attack