Defense Secretary Donald Rumsfeld opened his Senate panel testimony Friday by apologizing for the abuse of Iraqi detainees by American guards and suggested they should be compensated for their suffering.

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In his opening statement to the Senate Armed Services Committee, Rumsfeld called the treatment of Iraqi prisoners at Abu Ghraib prison "fundamentally un-American."

"These events occurred on my watch. As secretary of defense, I am accountable for them and I take full responsibility," Rumsfeld said. "I feel terrible about what happened to these Iraqi detainees. To those Iraqis who are mistreated by American forces I offer my deepest apology."

At the same time, he brushed aside Democratic demands for his resignation. Asked whether he could remain effective in his post, he said if he believed he could not, "I'd resign in a minute."

"I would not resign simply because people try to make a political issue out of it," he said in pointed rebuttal to the many Democrats who have called on him to step down.

Rumsfeld's apology came a day after President George W. Bush apologized to King Abdullah of Jordan and days after the publication of photos showing smiling American guards alongside naked, hooded Iraqi prisoners put in sexually suggestive poses.

His mention of compensation was a first for U.S. officials.

"I'm seeking a way to provide appropriate compensation to those detainees who suffered such grievous and brutal abuse and cruelty at the hands of a few members of the United States armed forces," Rumsfeld said.

"It's my intention to see that we do do it because it's the right thing," he said.

The defense secretary, who later testified for the House Armed Services Committee, warned the Senate panel that there are even worse images, including video, that he has seen and that has not been released to the public yet.

"There are a lot more photographs and videos that exist," he said. "If these are released to the public, obviously it's going to make matters worse."

Rumsfeld, sitting alongside a group of military leaders that included Joint Chiefs Chairman Gen. Richard Myers, was grilled by senators from both parties, the most notable exchange coming with Sen. John McCain, a Republican from Arizona. McCain repeatedly pressed Rumsfeld over the chain of command at Abu Ghraib prison, including what orders the guards accused of abuse would have been following.

Rumsfeld said the guards accused in the abuse were military police and were not trained to interrogate. He said they are ordered to follow the guidelines of the Geneva Conventions.

But Rumsfeld refused the suggestion of Democratic Sen. Robert Byrd of West Virginia that the military only reacted after the media reported on the photos of the abuses. He said despite the "despicable" actions of a few, many personnel at the prison acted responsibly, including the soldier who reported the allegations.

Rumsfeld said when a U.S. soldier came forward in January with allegations of abuse, U.S. military officials "told the world" about them in a Baghdad news conference and said they were being investigated. He said the idea that the story was "broken" by the media isn't true.

The Red Cross earlier said it had warned U.S. officials about alleged abuses more than a year ago. Rumsfeld said the agency's report was "helpful," and that officials at Abu Ghraib prison began making "corrections" based on the agency's recommendations.

Six U.S. soldiers are facing criminal charges and others have been reprimanded.

Rumsfeld said he's naming several senior former officials to look at the investigations that are already under way -- and see if additional probes need to take place. He said the department also needs to review its "habits and procedures."

Protesters Interrupt Testimony

Minutes after Rumsfeld apologized, he was interrupted by a group of protesters, (pictured, right) in the hearing room, demanding investigation of what they described as "other abuses in Iraq."

The protesters held signs and wore shorts that said "Fire Rumsfeld!" and chanted "War Criminal!"

The protesters were quickly escorted from the hearing room, and testimony resumed.

Rumsfeld On Not Alerting Congress

Rumsfeld told the panel he "failed to recognize" how important it was to bring the abuse matter to the attention of those at the "highest level -- including the president and members of Congress."

Bush, in apologizing on Thursday, said he supported Rumsfeld staying on his Cabinet but said "I should have known" about the pictures and the military's report, both of which were first made public in the media.

Many members of Congress are unhappy the secretary didn't share information about the abuse of prisoners with them before it became public. Many Democratic lawmakers called for Rumsfeld to resign, and some suggested he be fired if he does not resign.

McCain said it's premature to talk about Rumsfeld resigning. Sen. John Warner, R-Va., the chairman of the Senate Armed Services Committee, said he hasn't lost confidence in Rumsfeld -- "at this point."

Just hours before Rumsfeld testified, The New York Times ran an editorial headlined "Donald Rumsfeld Should Go."

Warner: 'Most Serious Military Conduct' He's Seen

Before Rumsfeld spoke, the chairman of the Senate Armed Services Committee said it's as serious an issue of "military misconduct" as he's ever seen in his 60 years following military procedure.

Warner opened the hearing by saying the allegations could seriously affect U.S. relations with other nations and put U.S. forces in danger wherever they are.

The panel's ranking Democrat, Sen. Carl Levin of Michigan, said the allegations have made prospects for success in Iraq even tougher.

Levin also said when top Pentagon officials appeared at a congressional hearing just hours before images of the alleged abuse were aired, they made no mention of the allegations.

Rumsfeld On Future Of Iraq

Rumsfeld said despite Iraqi prisoner abuse, the coalition is sticking to its timetable for Iraq.

In testimony to a Senate panel, Rumsfeld said the allegations shouldn't affect the scheduled June 30 transfer of power to the Iraqis.

Rumsfeld also said he's seen no "shift" in support from coalition countries for post-war Iraq in light of the allegations.

And he said more nations may get involved if the United Nations approves a resolution calling for more international support.

British Investigating New Abuse Claims

A British tabloid is detailing what it says are more claims of Iraqi prisoner abuse by British troops.

The Daily Mirror quotes an unnamed British soldier, who said he saw four brutal beatings of prisoners during his deployment in southern Iraq.

The source said British troops regularly placed sandbags over captives' heads and hit their faces, and that officers sanctioned such actions. He said British soldiers punched and kicked prisoners -- and one corporal poked a detainee's eyes until the man screamed.

British authorities are investigating photos published in the Daily Mirror last week, allegedly showing soldiers threatening and urinating on prisoners.

British authorities said they're questioning the soldier who made the new abuse claims. The Daily Mirror identified him only as "Soldier C."