US forces in Iraq kept detainees with only bread and water for up to 17 days in 2004, a newly-released report says.
US soldiers maintain they were following orders
The Special Operations troops stripped inmates naked and drenched them with water before interrogation in overly air-conditioned rooms, it said.
The report, by Brig Gen Richard Formica, says troops were not to blame - they had received the wrong advice.
It is the latest in a series of inquiries into the alleged abuse or killing of Iraqis by coalition forces.
Several US soldiers have been jailed for their role in abusing inmates at Baghdad's Abu Ghraib prison.
Images of the abuse caused an international outcry - but most defendants say they were following orders.
Gen Formica's report was completed in November 2004.
It was released for the first time on Friday following a request by the American Civil Liberties Union.
Other instances of abuse included:
- prisoners locked for as many as seven days in cells so small they could neither stand nor lie down
- loud music played into the cells
- prisoners made to kneel for long periods
Gen Formica said the abuse at the hands of the troops from the Combined Joint Special Operations Task Force - Arabian Peninsula had occurred from February to May 2004.
They had based their interrogation on policy guidance from September 2003 - which was rescinded a month later by the then top US commander in Iraq, Lt Gen Ricardo Sanchez.
Images of abuses at Abu Ghraib shocked the world
The soldiers believed the techniques had been approved, the 75-page, heavily redacted report says.
Gen Formica said what the troops had done was wrong, but it did not amount to deliberate abuse.
"I didn't find cruel and malicious criminals that are out there looking for detainees to abuse," Gen Formica told reporters on Friday.
He said it was regrettable that the soldiers had been given the wrong policy.
But a lawyer for ACLU said the report demonstrated that the abuse was "widespread and systemic".
The Abu Ghraib scandal came to light in April 2004 after images emerged of US troops abusing prisoners.
The footage included naked prisoners placed in humiliating positions and detainees cowering from aggressive dogs.
Eleven US soldiers have been convicted in connection with the Abu Ghraib abuse.
The former head of the interrogation centre at the prison Lt-Col Steven Jordan is the highest-ranking official to be charged.