Alexandria, Va. ? Convicted Sept. 11 conspirator Zacarias Moussaoui says he lied on the witness stand about being involved in the terrorist plot and wants to withdraw his guilty plea and go to trial. The judge turned him down.

Moussaoui said he was “extremely surprised” that he was sentenced to life in prison instead of execution and now believes he can get a fair trial from an American jury.

In a motion filed Monday, Moussaoui said he testified on March 27 that he was supposed to hijack a fifth plane on Sept. 11, 2001, and fly it into the White House “even though I knew that was a complete fabrication.”

A federal court jury spared the 37-year-old Frenchman the death penalty last Wednesday. On Thursday, U.S. District Judge Leonie Brinkema gave him six life sentences, to run as two consecutive life terms, in the federal supermax prison at Florence, Colo.

As she handed down the sentence, Brinkema told Moussaoui that he could appeal the life term but that she doubted he would win. “I believe it would be an act of futility,” she said.

The judge also pointed out that, although he could appeal the sentence, he had lost his right to appeal his conviction when he pleaded guilty in April 2005. “You waived that right,” she said.

“At the time I entered my guilty plea, my understanding of the American legal system was completely flawed,” Moussaoui said.

On Monday, Brinkema said that his request to set aside his guilty plea and go back to trial on the facts of the case was “too late” under federal rules and must be rejected.

Explaining his latest reversal, Moussaoui said in an affidavit:

“I had thought I would be sentenced to death based on the emotions and anger toward me for the deaths on Sept. 11. But after reviewing the jury verdict and reading how the jurors set aside their emotions and disgust for me and focused on the law and the evidence … I now see that it is possible that I can receive a fair trial even with Americans as jurors.”

Moussaoui’s court-appointed lawyers told the court that they filed the motion even though a federal rule “prohibits a defendant from withdrawing a guilty plea after imposition of sentence.” They did so anyway, they said, because of their “problematic relationship with Moussaoui” and the fact that new lawyers have yet to be appointed to replace them.

The defense lawyers were not immediately available for comment Monday.

Brinkema said that they would be replaced after they filed any appeal Moussaoui might want.