Defense Secretary Donald Rumsfeld has apologized to Iraqi prisoners abused by U.S. soldiers and accepted full responsibility for the scandal surrounding the mistreatment.

Mr. Rumsfeld tells Congress he feels terrible about the cases of abuse that have generated worldwide controversy. He says he accepts full responsibility.

"These events occurred on my watch. As secretary of defense, I am accountable for them and I take full responsibility."

Mr. Rumsfeld says the Pentagon is exploring possible compensation for the victims. In the meantime, he says he has ordered formation of a special independent commission to investigate actions taken by defense officials. He also apologized to the Iraqi prisoners who have been mistreated.

"To those Iraqis who were mistreated by members of the U.S. armed forces, I offer my deepest apology."

Defense officials say they learned of the incidents of abuse in January and immediately launched investigations. But public outcry only erupted recently after photos of the abuse emerged, many of them showing the sexual humiliation of prisoners.

Mr. Rumsfeld says he made a mistake in not alerting the president and Congress to the volatile nature of the abuses earlier.

"I failed to recognize how important it was to elevate a matter of such gravity to the highest levels, including the president and members of Congress...I wish we had known more sooner and been able to tell you more sooner."

Mr. Rumsfeld reveals there are more photos and even videos that have not yet reached the news media.

"Beyond abuse of prisoners, there are other photos that depict incidents of physical violence towards prisoners, acts that can only be described as blatantly sadistic, cruel and inhuman."

Members of Congress have voiced outrage over the abuse cases. Some say the incidents have endangered the lives of American soldiers in Iraq while tarnishing the United States' image. Others have decried what they see as an apparent breakdown in military leadership.

Senator Robert Byrd, a Democrat, blasted the Bush administration for allegedly trying to shirk responsibility.

"I see arrogance and a disdain for Congress. I see a misplaced bravado and an unwillingness to admit mistakes."

There have been calls by some Democratic lawmakers for Mr. Rumsfeld to resign, a call echoed by protesters who briefly disrupted Friday's Congressional hearing.

But the defense secretary says he will not quit for purely political reasons.

"Needless to say, if I felt I could not be effective, I'd resign in a minute. I would not resign simply because people try to make a political issue out of it."

President Bush has voiced support for the defense secretary, calling him a valuable member of his cabinet.