The judge hearing the first US war-crimes trial since World War II has banned evidence interrogators obtained from Osama bin Laden's driver, ruling that he had been subjected to ''highly coercive'' conditions in Afghanistan.

But Judge Keith Allred left the door open for the prosecution to use statements that Salim Hamdan made at Guantanamo Bay, despite defence claims that all his statements were tainted by alleged abuse, including sleep deprivation and solitary confinement.

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.

He faces a maximum life sentence if convicted of conspiracy and aiding terrorism.

The chief prosecutor for the tribunals, Colonel Lawrence Morris of the US Army, said the loss of some of Hamdan's statements would not prevent the trial from going ahead.

Outside the tribunal, he said, ''It does not reduce my confidence in our ability fully to depict Mr Hamdan's criminality.''

The judge said the prosecution cannot use a series of interrogations at Bagram air base and Panshir, Afghanistan, because of the ''highly coercive ... conditions under which they were made''.

At Bagram, the judge found that Hamdan a Yemeni with a Year 4 education had been kept in isolation 24 hours a day with his hands and feet restrained, and armed soldiers had prompted him to talk by kneeing him in the back. His captors at Panshir had repeatedly tied him up, put a bag over his head and knocked him to the ground.

Deputy chief defence counsel Michael Berrigan described the ruling as a significant blow to the tribunal system which allows hearsay evidence and evidence obtained through coercion. ''It's a very significant ruling because these prosecutions are built to make 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 US bases at the weekend.

Hamdan's lawyers succeeded in barring others, including one who had friends working at the Pentagon on September 11, 2001, and another who once taught a course taken by a person who is now one of the Government's key witnesses against Hamdan.

Yesterday marked the first time after years of pretrial hearings and legal challenges that any prisoner had reached this stage of military legal process.

The US plans to prosecute about 80 Guantanamo Bay prisoners, including the self-proclaimed mastermind of the September 11 attacks and four alleged co-conspirators. AP