A picture is beginning to emerge of the chaotic conditions inside Baghdad's Abu Ghraib jail at the time photos of US soldiers abusing prisoners were taken.
Iraqi prisoners were often kept naked, a report found (AP Photo/Courtesy of The New Yorker)
Former prison commanders have told of a violent atmosphere of rioting, with guards - heavily outnumbered by inmates - showing disdain for Iraqi prisoners.
The International Committee of the Red Cross said it had been aware of the abuses and had urged US authorities to act.
The US military told BBC News Online that about 8,000 inmates are currently being held in 14 separate jails. One of the biggest is Abu Ghraib in western Baghdad.
They said the great majority of prisoners were male "security internees" - people considered a possible threat to the coalition.
A US National Guard officer who commanded a military police company in Abu Ghraib, Lt Michael Drayton, said that, at the time of the abuse, there was an "overwhelming" inflow of such prisoners, creating a chaotic atmosphere in the prison.
He told Reuters news agency that military police (MP) guarding the prisoners were working up to 18 hour shifts.
"At any time we may have had 250 ...MPs, and you had over 7,000 security detainees and 400 to 500 actual [convicted] prisoners. You had to make things up as you go," he said.
"You get the feeling of being overwhelmed, because you were overworked and it was pretty frustrating."
Lt Drayton - who was stationed at the prison from November to March - condemned the actions of the men and women, from a different unit, who photographed Iraqis at Abu Ghraib in humiliating positions.
But at the same time, he spoke of the "frustration factor" in dealing with the prisoners.
"You got to understand - although it seems harsh - the Iraqis, they only understand force," he told Reuters.
"If you try to talk to them one on one as a normal person, they won't respect you. They won't do what you want ..."
8,000 prisoners held in 14 separate jails
Of those 15 are common criminals; 10 are women
Three main prisons - Abu Ghraib and Camp Cropper in west Baghdad; Camp Bucca, near Umm Qasr - hold inmates for extended periods
Almost all inmates are "security internees"- suspected of posing a threat to the coalition
He spoke of two riots which resulted in members of his team killing Iraqi prisoners.
"These prisoners were throwing bricks and hitting soldiers and causing bodily harm, so the guys did have the right to take them down and they did," he said.
An official report found numerous incidents of sadistic and wanton abuse of prisoners by US soldiers between October and December 2003.
Much of the abuse was sexual, with prisoners often kept naked and forced to perform simulated and real sex acts.
The army reserve general whose soldiers were photographed committing the abuses, believes they may have been encouraged by military intelligence officers running interrogation units.
Brig Gen Janis Karpinski, now suspended, said intelligence staff discouraged visits to the unit as they would interfere with interrogations, and went "to great lengths" to keep out the International Committee of the Red Cross (ICRC).
Staff Sergeant Ivan Frederick - one of the army reservists under investigation - appears to corroborate the claim of military intelligence involvement.
In e-mails home at the time, he said he had questioned some of the things he saw, according to the New Yorker magazine.
He described "such things as leaving inmates in their cell with no clothes or in female underpants, handcuffing them to the door of their cell."
"The answer I got was, 'This is how military intelligence wants it done'," he reportedly added.
Private military contractors have also been implicated in the abuse.
The report named an interrogator and translator in the humiliation of hooded and naked prisoners.
One contractor, working for the Central Intelligence Unit, is being investigated over the death of a prisoner in November.