The US Defense Secretary Mr Donald Rumsfeld took responsibility this evening for the abuse of Iraqi prisoners by US personnel and offered his "deepest apology" to the victims in the face of partisan demands that he step down.
"These events occurred on my watch as secretary of defense. I am accountable for them. I take full responsibility," Rumsfeld told the Senate Armed Services Committee.
"I feel terrible about what happened to these detainees. They are human beings, they were in U.S. custody, our country had an obligation to treat them right. We didn't. That was wrong," he said.
"To those Iraqis who were mistreated by members of the US armed forces, I offer my deepest apology."
Mr Rumsfeld, lacking his trademark bravado, said he had ordered the formation of a special commission to investigate the actions. But Arizona Sen. John McCain said Americans needed all the available information at once.
Several Democrats, including presidential candidate Mr John Kerry, have called for Mr Rumsfeld's resignation because of the physical and sexual abuse of Iraqis held at the Abu Ghraib prison west of Baghdad, which had previously served as a torture center under deposed Iraqi President Saddam Hussein.
However, President Bush has said he retains confidence in his defense secretary.
The committee chairman, Virginia Republican Sen. John Warner, said the abuse, vividly depicted in photographs of naked Iraqi detainees being mocked, humiliated and sexually abused by U.S. personnel, represented as serious a case of military misconduct as he had ever seen in his long career.
Michigan Democratic Sen. Carl Levin called the abuse "depraved and despicable." He said Congress needed to know how far up the chain of command the abuse went, whether it was part of a conscious policy, condoned by top officials, of softening up detainees before interrogation.
So far, six people have been criminally charged and six military personnel have been reprimanded.
Massachusetts Democratic Sen. Edward Kennedy said Mr Rumsfeld had shown a disregard for the Geneva Convention that protects the rights of prisoners. He asked how long Rumsfeld had known about the abuses and kept them secret.
Mr Rumsfeld said the US military had announced the allegations of abuses as soon as they were known. "They weren't hiding anything. They disclosed it to the world."
Hecklers shouting slogans interrupted the session shortly after Rumsfeld began his opening statement.
The defense secretary sat calmly, sipping his water, as they were peaceably
removed from the chamber.
Mr Rumsfeld said there were many more photographs and video tapes that have not been published showing cruel and sadistic acts by US personnel.