The disclosure was made Thursday in a court filing that seeks a new deadline to challenge evidence against Umar Farouk Abdulmutallab. The deadline is Friday.
Abdulmutallab is accused of trying to set off a bomb hidden in his underwear aboard a flight from Amsterdam to Detroit last year.
He's due in federal court Monday for a pretrial hearing.
On Christmas Day 2009, Abdulmutallab attempted to blow up a Northwest Airlines flight he was sitting on as it approached Detroit Metro Airport. But the bomb he was hiding in his underwear failed to explode.
He told federal agents shortly afterward that he had been trained and instructed in the plot by al Qaeda operatives in Yemen.
Abdulmutallab has been cooperating with the FBI, providing information about his contacts in Yemen and the al Qaeda affiliate that operates there. Abdulmutallab has turned against the cleric who claims to be his teacher, al-Awlaki, and has helped the U.S. hunt for him in Yemen.