WASHINGTON, May 8 — Zacarias Moussaoui added another bizarre chapter to his own case today when he asked to withdraw his guilty plea to terrorism-related charges, saying he is now convinced he can get a fair trial "even with Americans as jurors."

Just five days after a jury imposed a life sentence on him for concealing his knowledge of the Sept. 11 attacks, Mr. Moussaoui told Federal Judge Leonie M. Brinkema that he claimed to be a member of the plot "even though I knew that was a complete fabrication."

Mr. Moussaoui told Judge Brinkema, in what appeared to be a futile motion to withdraw his plea, that he had not trusted the American legal system because he was not assigned a Muslim lawyer, and that his days in solitary confinement had provoked him to fight that system.

The jurors' decision to spare his life made him look at his situation anew, Mr. Moussaoui said. He said he would welcome a trial where he could show he was not part of the 9/11 plot "because I now see that it is possible that I can receive a fair trial even with Americans as jurors."