TORONTO - Three Canadian journalists are being barred from Guantanamo Bay, where they have been covering pre-trial war-crimes hearings for Omar Khadr, the Pentagon said Thursday.

The reporters for the Toronto Star, Globe and Mail, and Canwest News Service breached a ban on identifying a witness, according to the Pentagon.

"Your reporters published the name of a witness whose identity was protected in court," a letter handed to the journalists stated.

"As a result of these violations, these individual reporters are barred from returning to cover future military commissions proceedings."

For the past eight days, Khadr's defence lawyers have been trying to establish the Canadian was tortured into making incriminating statements.

Among the witnesses was a former interrogator at Bagram prison in Afghanistan, where Khadr was taken after his capture in July, 2002.

The man testified Thursday to scaring Khadr by telling the badly wounded 15-year-old a "fictitious" story of an Afghan boy in U.S. custody who was gang-raped and died.

The Pentagon wanted him identified only as Interrogator No. 1 and forbade reporting his name, which has been widely available through his previous prosecution and conviction for detainee abuse.

He has also previously given an interview to the Star.

Toronto Star reporter Michelle Shephard, who has written a book on Khadr and his family, called the decision "ridiculous."

The paper's editor, Michael Cooke, denounced the ban.

"This is grossly unfair," Cooke said. "The Star will object to this decision."

Also barred were the Globe and Mail's Washington correspondent, Paul Koring, and Canwest's Steven Edwards.

Canwest vice-president Scott Anderson said from Ottawa he had not yet had a chance to talk about the issue with Edwards.

"It's critical that we find out what happened here," Anderson said.

"Obviously there was some misunderstanding on one side or another."

Globe foreign editor, Stephen Northfield, said the paper "would appeal this decision."

The New York-based American Civil Liberties Union condemned the Pentagon's ruling as "absurd" and "nonsensical," saying it would discourage reporting on the internationally condemned military commissions.

"No legitimate government interest is served by suppressing information that is already well known," said Jameel Jaffer, the union's deputy legal director.

"We strongly urge the Defence Department to reconsider its rash, draconian and unconstitutional decision to bar these four reporters from future tribunals."

Carol Rosenberg, a reporter from the American newspaper, the Miami Herald, who has extensive experience covering the commissions, was also told she may not return.

Rosenberg declined to discuss the situation, referring calls to the Herald's managing editor, who did not immediately return a call for comment.

The ban does not extend to the media outlets, only to the reporters involved.

However, media organizations themselves could be barred should there be "future violations," the letter warns.

The letter also states the reporters can appeal the decision to the deputy assistant secretary of defence for media operations.

The hearings have wrapped up -- it was not immediately clear when they will resume -- and the media on the U.S. naval base were all expected to leave Friday.

Khadr's trial -- he is accused of throwing a grenade that killed an American soldier and blinded another -- had been due to start in July.