GUANTANAMO BAY NAVAL BASE, Cuba — A former FBI agent testifying at the first Guantanamo war crimes trial said interrogators did not advise detainees here of any rights because the military prison is dedicated to intelligence gathering, not law enforcement.

An Al Qaeda expert and star witness for the prosecution, Ali Soufan, said yesterday the Guantanamo Bay Navy base is the only place in the world where he has not informed suspects of a right against self-incrimination.

“The way it was explained to us is Guantanamo Bay is an intelligence collection point,” he said.

Defense lawyers asked the judge in Salim Hamdan’s trial to throw out all the Guantanamo interrogations, arguing that intelligence-gathering sessions should not be used against him in court. But Judge Keith Allred, a Navy captain, ruled Monday that constitutional protections against self-incrimination do not apply to the man declared an “enemy combatant.”

Mr. Hamdan, a former driver for Osama bin Laden, is charged with conspiracy and aiding terrorism. His lawyers have cast him as a low-level employee of the terrorist leader without any role in Al Qaeda.

Other agents from the FBI and the Naval Criminal Investigative Service who interrogated Mr. Hamdan said at pretrial hearings last week that they were instructed not to advise Guantanamo detainees of rights, but Mr. Soufan is the first to provide a reason.

Mr. Soufan said the Guantanamo policy was an exception to a practice he followed even in Mr. Hamdan’s native Yemen, where he interviewed suspects in the investigation into the 2000 bombing of the USS Cole.

He testified today about two interrogations of Mr. Hamdan in 2002. A judge’s ruling is pending on whether to admit a third interrogation he conducted in May 2003, as defense lawyers review hundreds of pages of newly released prison records for evidence of coercion.

Mr. Soufan told the court Mr. Hamdan acknowledged moving Mr. bin Laden to a safer location days before the September 11, 2001 attacks because the Al Qaeda chief said “an operation was on its way.”

Mr. Soufan said he gained Mr. Hamdan’s confidence by helping to arrange for him to speak with his wife by phone and providing a car magazine and fast food such as McDonald’s fish sandwiches.

The judge suppressed other statements by Mr. Hamdan in Afghanistan because he made them under “highly coercive” conditions including isolation and beatings.

In opening arguments yesterday, prosecutors said Mr. Hamdan helped Mr. bin Laden evade American retribution after the September 11, 2001 attacks and ferried weapons for the Taliban in Afghanistan.

“You will not see evidence from the government that the accused ever fired a shot,” a prosecutor and Navy Lieutenant Commander Timothy Stone said. “But what you will see is testimony regarding the accused’s role in Al Qaeda, how he became a member of Al Qaeda and how he helped, facilitated, and provided material support for that organization.”

Two American military officers testified that two surface-to-air missiles were in the car Mr. Hamdan was driving when Afghan forces captured him at a roadblock in November 2001.

Mr. Hamdan faces a maximum life sentence if convicted. The trial is expected to take three to four weeks. American says it plans to prosecute about 80 prisoners at Guantanamo.