A Briton and a Canadian who say they were tortured into false confessions by Saudi authorities will not be allowed to testify at the trial of a man accused of joining Al Qaeda and plotting to assassinate President Bush, a judge ruled Monday.

Lawyers for Ahmed Omar Abu Ali, an American on trial for numerous terrorism charges, had hoped the men's testimony would bolster Abu Ali's contention that he was tortured into a false confession.

Abu Ali, 24, confessed to the Saudis in July 2003 that he joined Al Qaeda while enrolled at a Medina university. He told them he was motivated by his hatred of the United States for its support of Israel and that Al Qaeda asked him to establish a terror cell in the United States.

He now says he falsely confessed only after being whipped and beaten by the Saudi security force known as the Mubahith.

Defense lawyer Khurrum Wahid said the testimony of the two men, Briton Ron Jones and Canadian William Sampson, was necessary to counter claims by Mubahith officials that they do not mistreat prisoners.

But U.S. District Judge Gerald Bruce Lee agreed with prosecutors, who argued that the only relevant question is whether Abu Ali was tortured, not whether Jones and Sampson were tortured.

Both Jones and Sampson said they falsely confessed to involvement in a 2000 car bombing in Riyadh. The Saudi government claims the car bomb stemmed from a feud among Western bootleggers; Jones and Sampson say it was the work of anti-Western fundamentalists. The two were granted amnesty and freed in 2003.

Also Monday, jurors heard videotaped testimony from a Mubahith general who said Abu Ali cooperated after interrogators assured him he would not be turned over to the United States for prosecution. Abu Ali was returned to the United States in February to face trial.

In the confession, Abu Ali said that the leader of an Al Qaeda cell in Medina, Ali Abd al-Rahman al-Faqasi, asked him "to go to America and he would be the leader" of an Al Qaeda cell and that the assassination of Bush would be among the cell's duties, according to the general, whose name was not released.

Abu Ali, who was born in Houston and grew up in Falls Church, faces up to life in prison if convicted.