GUANTANAMO BAY, Cuba–The judge in the first American war crimes trial since World War II has barred evidence from "highly coercive" interrogations of Osama bin Laden's driver following his capture in Afghanistan.

The chief prosecutor for the tribunals, U.S. Army Col. Lawrence Morris, said the loss of some of Salim Hamdan's statements will not keep the trial from going forward.

"It does not reduce my confidence in our ability fully to depict Mr. Hamdan's criminality," he told reporters. "We're fine.''

Hamdan, who was captured at a roadblock in Afghanistan in November 2001, pleaded not guilty at the start of a trial that will be closely watched as the first full test of the Pentagon's system for prosecuting alleged terrorists, including Toronto-born Omar Khadr, who was reportedly subjected to sleep deprivation at Guantanamo Bay.

The judge, navy Capt. Keith Allred, said the prosecution cannot use a series of interrogations of Hamdan at Bagram air base and Panshir, Afghanistan, because of the "highly coercive environments and conditions under which they were made."

At Bagram, Hamdan says he was kept in isolation 24 hours a day with his hands and feet restrained, and armed soldiers prompted him to talk by kneeing him in the back.

He says his captors at Panshir repeatedly tied him up, put a bag over his head and knocked him to the ground.

His lawyers have alleged other abuse including sleep deprivation and solitary confinement.

The judge did leave the door open for the prosecution to use other statements Hamdan gave elsewhere in Afghanistan and at Guantanamo. Defence lawyers asked Allred to throw out all of his interrogations, arguing he incriminated himself under the effects of abuse.

Hamdan, a Yemeni in his late 30s, faces a maximum life sentence, if convicted, of conspiracy and aiding terrorism.

Michael Berrigan, deputy chief defence counsel, described the ruling as a major blow to the tribunal system that allows hearsay and evidence obtained through coercion.

"It's a very significant ruling because these prosecutions are built to take full advantage of statements obtained from detainees," he said.

A jury of six officers with one alternate was selected from a pool of 13 flown in from other U.S. bases over the weekend.

Hamdan has been held at Guantanamo since May 2002.

A challenge filed by his lawyers resulted in a 2006 Supreme Court ruling striking down the original rules for the military tribunals. Congress and U.S. President George W. Bush responded with new rules, the Military Commissions Act.

Hamdan met bin Laden in Afghanistan in 1996 and began working on his farm before winning a promotion as his driver.