The scandal over the abuse of Iraqi prisoners deepened today after a US newspaper unearthed documents which including hundreds of new images of torture at the hands of the US military at the Abu Ghraib prison.

The photographs and short digital video clips, some of which were published today in The Washington Post, provide the most detailed picture yet of what took place at the prison and outline a broader pattern of abuse than those images already in the public domain.

The photographs of US soldiers abusing inmates have already scandalised the American military and led to calls for the resignation of Donald Rumsfeld, the US Defence Secretary.

The Post has also seen statements from 13 former prisoners describing a variety of abuses including being sexually molested by female soldiers, threatened with rape and forced to eat food from toilets.

Some of the detainees described being abused as a punishment after they were caught fighting or with a prohibited item. Some claimed they were pressed to denounce Islam or were force-fed pork and alcohol.

The paper said that the testimony of abuse obtained from the 13 detainees was part of evidence gathered by US Army investigators for the courts martial in Iraq of seven US soldiers charged with abusing detainees.

A Defence Department spokesman told the Post that the description of the photos and video clips seemed to match that of the graphic material shown privately to US senators and Congress members earlier this month.

The photographs and videos showed detainees cowering before dogs, being forced to masturbate, being hit or sexually assaulted by guards and threatened with a shotgun.

Six photographs printed on Post's website included one of a naked prisoner, smeared with what appeared to be excrement, being forced to walk a straight line in front of a baton-wielding guard.

In another a detainee kneels with his hands apparently tied behind his back as a large, black dog snarls only a metre or so from his face.

"They forced us to walk like dogs on our hands and knees," said Hiadar Sabar Abed Miktub al-Aboodi, detainee No 13077.

"And we had to bark like a dog, and if we didn't do that they started hitting us hard on our face and chest with no mercy.

"After that, they took us to our cells, took the mattresses out and dropped water on the floor and they made us sleep on our stomachs on the floor with the bags on our head and they took pictures of everything."

One detainee said that he witnessed a US Army translator having sex with a boy of between 15 and 18 at the prison, who was screaming with pain.

Another detainee described several soldiers, one of whom was named in the Post, sodomising another detainee with a phosphoric light.

The Post also released short video clips of abuse and sexual humiliation. One showed five hooded and naked detainees standing against the wall in the darkness, each masturbating, with two other hooded detainees crouched at their feet.

Another showed a prisoner handcuffed to the outside of a cell door, slamming his head into the green metal, the newspaper said.

As the new images were published, 454 Iraqi prisoners in six busloads were freed from the Abu Ghraib prison. Almost 300 prisoners were freed last Friday.

American officials had been ordered to "thin out" the numbers at the prison, notorious also under Saddam Hussein, which is overcrowded with as many as 3,000 Iraqis who the US say are suspected militants. Most of the prisoners have not been charged or tried.

On Wednesday, Specialist Jeremy Sivits was sentenced to a maximum 12-month jail term after he pleaded guilty to mistreating Abu Ghraib prisoners last November. Other courts martial are to follow.

The subject of how Iraq is progressing towards the scheduled handover of power on June 30 will be addressed in a hearing today before the House Armed Services Committee in Washington.

Witnesses include General Richard Myers, chairman of the Joint Chiefs of Staff, Peter Schoomaker, the US Army Chief of Staff and Marine Commandant General Michael Hagee.

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