An FBI agent says a Nigerian man accused of trying to blow up a Detroit-bound airliner on Christmas 2009 was not given his Miranda rights because authorities feared there might be more attacks to come.

Agent Timothy Waters testified Wednesday that Umar Farouk Abdulmutallab might not have cooperated if given the option to remain silent. Waters says al-Qaida often stages coordinated attacks, and that the government needed to know if there were other planes with "suicide bombers" that day.

Abdulmutallab is charged with trying to detonate a bomb in his underwear on an Amsterdam-to-Detroit flight. He wants incriminating statements thrown out because he wasn't given his Miranda rights immediately after being treated for burns.

Earlier, a judge denied Abdulmutallab's request to be judged by Islamic law.