The US military in Iraq has launched a damage limitation exercise following the outcry over images of US soldiers abusing prisoners.
Gen Miller "guarantees" such abuses will not happen again
They invited a group of journalists, including the BBC's David Willis, into Baghdad's Abu Ghraib prison - the jail at the centre of the allegations.
The new head of Iraq prisons, Gen Geoffrey Miller, has apologised for the abuse, saying it will not happen again.
Rights groups welcome the moves, but say they do not go far enough.
BBC correspondent David Willis says the US military is at pains to point out that systems of interrogation and detention have been drastically overhauled.
Chants and waves
During his visit to the sprawling Abu Ghraib prison - notorious for torture and executions during Saddam Hussein's leadership - our correspondent said a throng of detainees rushed to the barbed wire.
They were chanting and waving. One man used a loudspeaker to shout in faltering English, "Where's the freedom, Mr Bush?"
Another cried: "They taken away our freedom, our dignity and our rights."
At that point the marines leading the tour ordered the journalists back on the bus, said our correspondent.
The journalists were told they could not interview or film the detainees as it would be a breach of their rights under the Geneva Convention.
Gen Miller - who was previously in charge of the US military detention centre for terror suspects in Guantanamo Bay, Cuba - admitted that some of the treatment of prisoners had been illegal and unauthorised.
"I personally guarantee that this will not happen again," he publicly pledged.
Gen Miller said interrogation techniques such as sleep deprivation could now not be used without the permission of a senior officer.
Putting hoods over prisoners' heads was also now banned, he said.
He also vowed to halve the 3,800 prisoners in Abu Ghraib in the coming weeks and months.
MAJOR GENERAL GEOFFREY MILLER
54-year-old career military officer from Texas
Former commander at Guantanamo Bay in Cuba, where many suspected terrorists are held
Criticised by human rights groups for the detention system
Says he is "absolutely confident" in his Iraq recommendations
Graphic photographs obtained by US media show inmates being subjected to humiliation and psychological pressure by troops.
Some Iraqi prisoners also claimed they were beaten and stripped by US soldiers. They spoke of getting limited water, being kept outdoors or put in positions where the body will undergo stress, such as being ordered to stand still for extended periods or keep arms above their head.
In previous comments to journalists, Gen Miller was unapologetic about the use of tough interrogation tactics.
Interrogators are allowed to use "interrogation techniques that increase anxiety," he told journalists earlier in the week.
"There is aggressive conversation but we do not threaten... there is no physical contact between the detainees authorised and the interrogator. We do not use stress positions."
The former head of the prison, Brig Gen Janis Karpinski - who has been reprimanded for command failures - has accused military intelligence officers at the prison of going "to great lengths" to exclude the International Committee of the Red Cross (ICRC) from the interrogation wing.
But an ICRC spokesman, Roland Huguenin-Benjamin, told BBC News Online they were not aware of being actively discouraged from visiting parts of the prison.
"The ICRC has a mandate to see prisoners of war and security detainees, and we had free access to those people," he said.
Photos of the treatment of Iraqi prisoners have shocked the world
"We were never given the impression that we would be prevented from going into a particular place.
"But after October, when the ICRC office was bombed, it became difficult for us to move about and perform at the level we would have wanted."
Amnesty International said Gen Miller's pledged changes were a step forward, but more needed to be done.
The rights group said it had been calling for a full investigation since raising allegations of torture and ill-treatment with coalition officials last summer.
"Yet still they are failing to stamp out these abuses," it said in a statement.