A leading human rights group has criticised US treatment of detainees in Iraq, as the UN opened a workshop focusing on abuses committed by the regime of Saddam Hussein.
The group says Iraqis have been detained in cruel conditions
Amnesty International has warned that the "conditions of detention Iraqis are held under... may amount to cruel, inhuman or degrading treatment or punishment, banned by international law".
The organisation says hundreds of people have been held without shelter or basic sanitation and denied access to lawyers.
But the Pentagon rejects the Amnesty allegations.
We don't hold these people any longer than necessary
Commander Chris Isleib,
US military spokesman
"The coalition forces act in a humane manner toward all prisoners," Commander Chris Isleib told BBC News Online, adding that the International Committee of the Red Cross carries out regular inspections.
"We follow international law to the letter," he said. He told the BBC that prisoners were separated by age, sex and rank and by the reason for their detention.
"We don't hold these people any longer than necessary," he said.
He said coalition forces had freed more than 11,000 people so far, even though under international law they could continue to hold detainees until there is a functioning Iraqi Government to take responsibility for them.
Amnesty International expressed particular concern about the conditions in which detainees are held.
The group said prisoners were bound so tightly with plastic handcuffs that many still showed scars on their wrists a month after their arrest.
We spent our first night in custody lying on the ground in a school. We had no access to a toilet and were given no food or water
Former prisoner quoted by Amnesty International
The group warned that a two-tier system was evolving, with prisoners in the Iraqi legal system being afforded proper protection while those in military detention were not.
"Some detainees fall into a 'black hole' detention centre at the [Baghdad International] airport; their family has no news of them and they are only entitled to a review of their detention within three weeks by a US military lawyer," the group said in a statement.
"Others arrested for similar offences are taken to Iraqi police stations and receive the protection of the procedures in the... Criminal Procedure Code... They are entitled to release if there is insufficient evidence against them," it added.
Amnesty criticised US search methods
The group collected testimony from former detainees for its statement.
"We spent our first night in custody lying on the ground in a school. We had no access to a toilet and were given no food or water," one of four brothers who was hooded and handcuffed on detention told the group.
Amnesty says that there has been looting as Iraqis are detained.
The human rights campaigners urged the US to give detainees access to family and lawyers and to investigate reports of mistreatment of prisoners, including death in custody.
Amnesty International wrote to the US administrator in Iraq, Paul Bremer, with its concerns last week. A spokesman said the group had not yet received a reply.
The spokesman, Alistair Hodgett, said it was coincidence that its statement was being released as the UN discussed human rights in the Saddam Hussein era.
"We are not trying to make a comparison," Mr Hodgett told BBC News Online. "It's a dead-end game of who's better, who's worse."
Vieira de Mello says 300,000 disappeared under Saddam Hussein
"The fact that there were abuses in the past does not excuse abuses now," he said.
The special United Nations human rights representative in Iraq, Sergio Vieira de Mello, opened the Baghdad workshop by highlighting the abuses that took place under the previous regime.
"Thousands of men, women and children from all walks of life... were held in secret detention centres, silenced, tortured, disappeared, raped and killed," he said.
"The only non-discriminatory policy of Saddam was the systematic, across-the-board violations of our most fundamental right: the right to life," he told the workshop.
The UN says at least 300,000 people disappeared in torture chambers and detention centres during Saddam Hussein's rule.