Human rights groups complained that their representatives were barred by the U.S.-led occupation authorities from the courtroom.

"Barring human rights monitors from the court martial is a bad decision in its own right," said Sarah Leah Whitson, executive director of Human Rights Watch's Middle East and North Africa division, in a statement.

"It also sends a terrible signal to Iraqis and others deeply concerned about what transpired in Abu Ghraib."

U.S. Captain Mark Doggett told the international watchdog that senior officers had discussed attendance by the group and other human rights organizations and decided not to permit their attendance for unspecified "security among other reasons".

"It is unreasonable to exclude Human Rights Watch and other rights monitors who have expertise in the abuses at the heart of the court martial," Whitson countered.

On Tuesday, May 18, the U.S. military took a group of journalists on a tour inside Abu Gharib in what was described as a charm offensive. The jail’s authorities, however, denied them interviews with the detainees.

‘Cover-Up’

The U.S. refusal to allow human rights organizations into the courtroom came as a U.S. soldier close to the brutal interrogations of Iraqi prisoners said dozens of soldiers were involved in the abuse.

"There's definitely a cover-up," Sgt. Samuel Provance told ABCNEWS. "People are either telling themselves or being told to be quiet."

Provance, 30, was part of the 302nd Military Intelligence Battalion stationed at Abu Ghraib last September.

"What I was surprised at was the silence."

"There's definitely a cover-up," said Provance

"The collective silence by so many people that had to be involved, that had to have seen something or heard something."

Provance, who ran the top secret computer network used by military intelligence at the prison, said the abuse and sexual humiliation of prisoners were authorized by the military commanders.

"Anything [the Military Police] were to do legally or otherwise, they were to take those commands from the interrogators.

"One interrogator told me about how commonly the detainees were stripped naked, and in some occasions, wearing women's underwear," Provance told the American network.

Provance also described an incident when two drunken interrogators took a female Iraqi prisoner from her cell in the middle of the night and stripped her naked to the waist. The men were later restrained by another MP.

He said he was intimidated and discouraged by his commanders not to speak his mind out.

"I feel like I'm being punished for being honest," Provance told ABCNEWS.

"You know, it was almost as if I actually felt if all my statements were shredded and I said, like most everybody else, 'I didn't hear anything, I didn't see anything. I don't know what you're talking about,' then my life would be just fine right now."

The New Yorker magazine dropped a bombshell Sunday, May 16, saying the torture was okayed  by Secretary of Defense Donald Rumsfeld.