WASHINGTON – A Virginia man accused of plotting with Al Qaeda to kill President Bush should be held indefinitely, federal prosecutors said yesterday in court filings that also rejected his contention that he was tortured while held in Saudi Arabia.

At a court hearing a day earlier in Alexandria, Va., 23-year-old Ahmed Abu Ali offered to display scars on his back as proof that he was tortured by Saudi authorities. In their filing yesterday, prosecutors said, “There is no credible evidence to support those claims.”

Mr. Abu Ali never complained about his treatment during several meetings with an American diplomat in Saudi Arabia, according to the filing. Moreover, an American doctor examined him Monday and found “no evidence of physical mistreatment on the defendant’s back or any other part of his body.”

Edward MacMahon, one of Mr. Abu Ali’s lawyers, said yesterday he had not seen the government’s motion and declined to comment. But on Tuesday, both Mr. MacMahon and defense lawyer Ashraf Nubani said they had seen the scars on his back. Mr. Nubani said they looked like whip marks.

Mr. Abu Ali would pose “an exceptionally grave danger to the community” if released before his trial, prosecutors said in yesterday’s filing in U.S. District Court in Alexandria. Mr. Abu Ali also would be unlikely to show up for his trial, they said.

Until now, the government has had little to say about the arrest and detention of Mr. Abu Ali in Saudi Arabia, where he was held for 20 months before being suddenly flown to America on Tuesday.

His lawyers and family allege the Saudis held him at the American government’s request and tortured him with the knowledge of American officials. Prior to Mr. Abu Ali’s return, a lawsuit filed on his family’s behalf in U.S. District Court in Washington sought information about his capture and treatment.

The government sought to have the case dismissed, but U.S. District Judge John Bates has declined, saying the family has presented circumstantial evidence to support their claims of torture.

Mr. Abu Ali was born in Houston and moved to Falls Church, Va., a Washington suburb. He was valedictorian of the Islamic Saudi Academy in Alexandria, then went to Saudi Arabia to study. He was arrested there in June 2003 but never charged.

[Yesterday, Senator Schumer, a Democrat of New York, called for the Justice Department to investigate the nature and funding of the Islamic Saudi Academy, saying the school has had connections to other terror suspects.

“We need to know if the Islamic Saudi Academy is another example of the Saudi government turning a blind eye to terrorism. I hope that the ISA is not another madrassa in the United States,” he said.]

Two different federal courts will consider Mr. Abu Ali’s case today. In Alexandria, he is due for a hearing on whether he should remain in custody until his trial. In Washington, Judge Bates has scheduled a hearing in the civil lawsuit.

Judge Bates wrote in December that there was “at least some circumstantial evidence that Abu Ali has been tortured during interrogations with the knowledge of the United States.”

In addition, Mr. Abu Ali’s family said a U.S. diplomat reported to them that Mr. Abu Ali said FBI agents who questioned him threatened to send him to the detention facility at Guantanamo Bay, Cuba, Judge Bates wrote.

He noted at the time that the government had not attempted to rebut the family’s claims. Since then, however, the Justice Department has filed a classified document seeking to justify its call for the civil case to be dismissed.

Morton Sklar, Mr. Abu Ali’s lawyer in the civil case, said his client’s return to America should not end the lawsuit. “Our main concern is that the United States government seems to have done a very effective job of diverting attention from its own responsibility for illegal conduct by focusing attention on the criminal charges,” Mr. Sklar said.

A Justice Department spokesman said he would have no comment before the hearing in the civil case.

To make its criminal case against Mr. Abu Ali, the government could have to disclose details about his detention that it has sought to keep secret.

In the indictment, the government alleges Mr. Abu Ali discussed assassinating Mr. Bush, conducting a terrorist attack in America, and establishing an Al Qaeda cell here.