The Washington Post says it has seen hundreds of videos and photos which show previously unseen abusive methods used at Baghdad's Abu Ghraib jail.
In sworn statements, detainees said they were beaten, sexually humiliated and force-fed pork and alcohol.
A video has also emerged showing a detainee being dragged along the floor.
The grainy image also shows another prisoner being slapped across the face, while one naked Iraqi crouches on the floor.
The new photos include one of a prisoner being menaced by a soldier with a dog.
In other abuses depicted in the latest pictures:
A naked prisoner who appears to be covered in excrement is paraded down a corridor
A hooded detainee is pictured in a state of collapse
A US soldier appears to be raining blows on detainees sprawled on the floor.
The Washington Post report also describes a video clip in which a shackled inmate repeatedly slams his bloody head against a metal door, before collapsing.
As the latest reports were published, US forces in Iraq began freeing 472 detainees from Abu Ghraib jail.
Six buses filled with Iraqis drove away from the prison gates in the first phase of the latest releases.
Correspondents say the Washington Post appears to have gained access to photos and video clips recently shown to members of Congress by the Pentagon but not made public.
The BBC's Clive Myrie, in Washington, says some US politicians are calling for all images and videos to be made public, in an attempt to draw a line under the scandal.
In the Washington Post's accounts, several Iraqi prisoners are quoted giving graphic details of abuse by US soldiers.
They ordered me to thank Jesus I'm alive
Iraqi detainee quoted by Washington Post
One detainee, named in the report as Ameen Saeed al-Sheik, said he was asked by a soldier whether he believed in anything.
"I said to him, 'I believe in Allah.' So he said, 'But I believe in torture and I will torture you.'"
He said one soldier struck his broken leg and ordered him to curse Islam.
"Because they started to hit my broken leg, I curse my religion," the paper quoted him as saying. "They ordered me to thank Jesus I'm alive."
Other detainees said they were stripped on arrival at the prison, forced to wear women's underwear and repeatedly humiliated in front of each other and American soldiers.
US Military Police Specialist Charles Graner - who has been charged over the scandal - was named in several of the reports.
One detainee accused him of repeatedly throwing prisoners' meals into the toilets and saying, "Eat it."
Spc Graner, who appears in a number of the photos from Abu Ghraib, has said he was following orders.
Spc Graner is one of seven US soldiers who have been ordered to stand trial on charges of abusing prisoners at Abu Ghraib jail.
One, Spc Jeremy Sivits, has already pleaded guilty at a court martial. He was jailed for a year, demoted and discharged from service.