NEW YORK — The self-described mastermind of the Sept. 11 attacks says a onetime Osama bin Laden spokesman who is on trial in New York had no role in planning military operations for al-Qaida.

Khalid Sheikh Mohammed said in a statement filed late Sunday in Manhattan federal court that Sulaiman Abu Ghaith served as an al-Qaida spokesman because he was “an eloquent, spellbinding speaker.” But Abu Gaith, Mohammed said, “was not a military man and had nothing to do with military operations.”

Abu Gaith, who is a son-in-law of bin Laden, is charged with conspiring to kill Americans.

Prosecutors say Abu Ghaith was part of al-Qaida’s deadly plot in his role as spokesman in fiery videos and as a motivational speaker at the group’s training camps in Afghanistan.