NEW YORK: The self-described mastermind of the Sept 11, 2001 terror attacks in the US on Sunday said the onetime Osama bin Laden spokesman who is on trial in New York had no role in planning military operations for Al Qaeda.

Khalid Sheikh Mohammed said in a statement filed in Manhattan federal court late Sunday that Sulaiman Abu Ghaith served as an Al Qaeda spokesman because he was "an eloquent, spellbinding speaker".

But Mohammed says Abu Ghaith "had nothing to do with military operations".

Abu Ghaith, who is a son-in-law of Osama, is charged with conspiring to kill Americans. He is the highest-level Al Qaeda figure to be tried in the US since the Sept 11 attacks.

Prosecutors say he was part of Al Qaeda's deadly plot in his role as spokesman in fiery videos and as a motivational speaker at the group's training camps in Afghanistan.

Abu Ghaith's lawyers have said the Kuwait-born imam made inflammatory remarks but didn't conspire to carry out terrorism.

Defence lawyers are seeking to use testimony from Mohammed, who is in a detention facility in Guantanamo Bay, Cuba. They would need US District Judge Lewis A. Kaplan's approval to introduce the information.

The defence has suggested Mohammed could help rebut the government's claim that Abu Ghaith must have known in advance of Al Qaeda's so-called shoe bomb airplane plots, including Richard Reid's attempt to carry one out in Dec 2001.

The statement from Mohammed filed Sunday consisted of answers he gave to questions posed by Abu Ghaith's lawyers.

In the statement, Mohammed said he never spoke with Abu Ghaith about the shoe bomb operation and added: "Those tasked with giving statements to the media do not necessarily know all the details of an operation and are sometimes even unaware of the very existence of the operation.''

Prosecutors rested their case Friday in the trial of Abu Ghaith. The defence case is due to start Monday.