Stunned by the U.S. military's abuse of Iraqi prisoners, lawmakers demanded answers Tuesday to how it happened. One lawmaker said he feared the abuses may be more widespread than first reported.

Sen. Edward Kennedy (search), D-Mass., emerged from a closed-door briefing of the Senate Armed Services Committee and said he feared that the allegations made public so far are "the beginning rather than the end" of the abuse allegations.

"This does not appear to be an isolated incident," Kennedy said. There might be other abuses at facilities in Iraq and possibly Afghanistan, he said.

But Sen. John McCain (search), R-Ariz., told reporters outside the hearing he was "extremely hopeful that ... this was not a widespread pattern of abuse and that the conduct of the overwhelming majority of Americans is honorable and decent."

McCain, who spent 5 1/2 years as a prisoner of war in Vietnam, added, however that the abuses themselves would not be tolerated or excused.

"The rules for the treatment of prisoners of war are very clear," McCain said. "There is no justification for this kind of treatment."

The Pentagon (search) sent several lower level uniformed military officials to Capitol Hill after being summoned by the committee. Chairman John Warner, R-Va., said the allegations, "if proven, represent an appalling and totally unacceptable breach of military conduct (search) that could undermine much of the courageous work and sacrifice by our forces in the war on terror."

As the committee met, Minority Leader Tom Daschle, D-S.D., said on the Senate floor that he wants Secretary of Defense Donald Rumsfeld to come to the legislative body "no later than the end of this week ... and explain to us what they know."

Among other things, Daschle said he wanted to know why President Bush was not earlier informed of a report that American soldiers had subjected detainees to blatant and sadistic abuse at the Abu Ghraib prison (search) and why Rumsfeld and Joint Chiefs of Staff Chairman Gen. Richard Myers have not yet read the two-month old report.

"Why, in other words, has there been this extraordinary disconnect, this unbelievable failure of communication, of oversight," Daschle said. "We cannot let this action go without doing all that we can to ensure that we understand all of the circumstances ... and be provided with ... specific and detailed response involving discipline."

White House spokesman Scott McClellan said Tuesday that Bush first became aware of the allegations of abuse some time after the Pentagon began looking into it but did not see the pictures until they were made public and did not learn of the classified Pentagon report until news organizations reported its existence.

On Monday, a Pentagon official said the U.S. military did a "top-level review" last fall of how its detention centers in Iraq were run, months before commanders first were told about the sexual humiliation and abuse of Iraqis that has created an international uproar.

Larry Di Rita, the top spokesman for Defense Secretary Donald H. Rumsfeld, said the review was done at the request of Lt. Gen. Ricardo Sanchez (search), the senior American commander in Iraq.

Di Rita did not say what prompted the review. He said it "drew certain conclusions," which later were taken into account by Maj. Gen. Antonio Taguba, who began an investigation on Jan. 31 focused on an unidentified soldier's report of prisoner mistreatment at Abu Ghraib prison.

That second probe led to findings of blatant and sadistic abuse by U.S. military police and perhaps others. It has drawn wide condemnation, particularly with the publication of photos documenting the mistreatment.

An attorney for a military police officer being investigated in the abuse probe, said on a morning news show that the photographs of the Iraq prisoners that have inspired widespread revulsion "were obviously staged" in order to manipulate the prisoners into cooperating with intelligence officials.

"They were part of the psychological manipulation (search) of the prisoners being interrogated," said Guy Womack, attorney for Charles A. Graner, Jr., a Greene County, Pa. corrections officer who was activated to the military in March 2003 and served at Abu Ghraib.

"It was being controlled and devised by the military intelligence (search) community and other governmental agencies, including the CIA," Womack said. The soldiers, he said, were simply "following orders."

On Capitol Hill, there was widespread concern. Republican Sen. Susan Collins of Maine said she fears that photos depicting Iraqi prisoners in U.S. custody apparently being sexually humiliated and physically abused, which have been widely broadcast on TV, could incite more violence against American troops in Iraq.

Sens. Chuck Hagel, R-Neb., and Jeff Bingaman, N.M., said the concern goes beyond the actions of a few soldiers.

"There is a bigger issue here," Hagel said Tuesday on the same news show. "Was there an environment, a culture that not only condoned this, but encouraged this kind of behavior? We need to look well beyond just the soldier. Who was in charge? Was there a breakdown in command here? ... We need to understand all the dynamics of this."

On March 20, criminal charges were filed against six military police officers. As many as three of the six cases have been referred to military trial, and others are in various stages of preliminary hearings, officials said.

In addition to the criminal cases, seven others — all military police — have been given noncriminal punishment — in six of the cases they got letters of reprimand. Some of the seven are members of the Army Reserve (search), according to a defense official who direct knowledge of the situation.

It was unclear whether others, including those in military intelligence, will face disciplinary action. The names of the seven have not been made public.