Usama bin Laden's former driver can ask senior Al Qaeda suspects imprisoned at Guantanamo for help in his war-crimes tribunal, a military judge said Wednesday, overruling concerns that communication between the detainees could threaten national security.

Yemeni detainee Salim Ahmed Hamdan is boycotting his trial, saying the military process is fundamentally unfair. The judge, Navy Capt. Keith Allred, said he hopes Hamdan will reconsider if he's given some opportunity to gather material for his own defense.

"I want to try to persuade Mr. Hamdan to come back to trial," Allred said at a pretrial hearing. "I sense this might make him feel he's doing something in his defense, that he's involved in the process."

Meanwhile, the judge kept Hamdan's case on track to be the first of the Pentagon's terrorism prosecutions at Guantanamo, scheduling the trial to begin on June 2 with or without the detainee's participation.

Hamdan refused Wednesday to leave his prison cell, and his defense attorneys also refused to participate in the pretrial hearing, a spectacle that puzzled the prosecutors.

"I'm a little confused, are they still representing Mr. Hamdan?," Army prosecutor Lt. Col. William Britt said.

Hamdan, 37, was captured at a roadblock in southern Afghanistan in November 2001, allegedly with two surface-to-air missiles in the car. He faces up to life in prison if the tribunal convicts him of conspiracy and supporting terrorism.

He has declared he will no longer participate in the proceedings despite entreaties from the judge to reconsider. Three other alleged Al Qaeda operatives also indicated they will boycott their Guantanamo trials.

The military says it plans to prosecute about 80 of the roughly 275 men held at Guantanamo on suspicion of terrorism or links to Al Qaeda or the Taliban. So far only detainee has been convicted — David Hicks, who served a nine-month prison sentence in his native Australia under a plea deal.