WASHINGTON - THE first Guantanamo Bay war crimes trial, of Osama bin Laden's former driver, can start next week, a federal judge ruled on Thursday, refusing to intervene in the military process backed by President George W. Bush and Congress.

United States District Judge James Robertson rejected a request from attorneys for Salim Hamdan, who drove for the Al-Qaeda leader in Afghanistan, to stop his trial while he challenges the military tribunal system.

Judge Robertson heard more than two hours of arguments from Hamdan's lawyers and the Justice Department over whether the trial should be delayed. It is due to start on July 21.

Hamdan, a Yemeni, would be the first prisoner tried in the US war crimes court at the Guantanamo naval base in Cuba.

There are about 265 detainees at base's prison camp, which was set up in January 2002 to hold terrorism suspects captured after the Sept 11 attacks by Al-Qaeda in 2001.

Most have been held for years without being charged and many have complained of abuse.

Hamdan's attorneys said a landmark Supreme Court ruling last month made clear the detainees are entitled to fundamental constitutional rights.

'Guantanamo once was a constitution-free zone. It no longer is,' Georgetown University law professor Neal Katyal, one of the lawyers for Hamdan, said in arguing for a delay.

But the judge sided with the arguments by Deputy Assistant Attorney General John O'Quinn, who said a 2006 law backed by Bush allows such challenges only after a trial takes place.

The Guantanamo trials are the first US war crimes tribunals since World War II. They were set up to try non-American captives whom the Bush administration considers 'enemy combatants' not entitled to the legal protections granted to soldiers and civilians.

Human rights groups have criticised the Guantanamo prison and trial system as inherently unfair. -- REUTERS