The disclosures made clear that suspected abuses by U.S. soldiers go well beyond those documented at the Abu Ghraib prison near Baghdad involving soldiers of a Maryland-based Army Reserve unit.
In addition to those cases, officials said, the Army has determined that one Iraqi prisoner who was shot to death was a victim of homicide. It has also turned over to the Justice Department the case of another Iraqi prisoner death at Abu Ghraib that involved a contract worker for the CIA.
Defense Secretary Donald H. Rumsfeld condemned the abuses as "deeply disturbing" and "un-American." He vowed that appropriate action would be taken.
"The actions by U.S. military personnel in those photos," Rumsfeld said, "do not in any way represent the values of our country or of the armed forces."
Members of Congress, shocked and angered by the allegations, set the stage for their own inquiry, calling for public testimony from Rumsfeld and top civilian Pentagon leaders.
Senior lawmakers expressed concern that the images of extreme humiliation could severely damage U.S. security and relations with the rest of the world, especially Arab nations.
Several demanded that Congress open a broad investigation into all U.S. detention facilities, to try to determine whether systemic problems led to widespread abuse of detainees.
Sen. John W. Warner, the Virginia Republican who is chairman of the Armed Services Committee, promised a "public hearing at the first opportunity we can" with Rumsfeld and other senior officials. Warner, a former Navy secretary, said he was determined to examine what he called "one of the most extraordinary chapters that I have thus far witnessed" in more than half a century of association with the U.S. military.
Emerging from classified briefings with Army officials, senators criticized military leaders for failing to tell Congress earlier about the allegations against U.S. soldiers at the Abu Ghraib prison.
The case has sparked five military inquiries and led to criminal charges against six soldiers from a Maryland-based military police unit, as well as career-ending reprimands for six of their superiors.
Graphic photos from the Abu Ghraib prison, now shown around the world, depict naked captives being subjected to sexual humiliations and other abuses. Some soldiers from the 372nd Military Police Company, based near Cumberland, are shown smiling and giving thumbs-up signs.
Bush's spokesman said the president was not shown the photos of the abused prisoners until after they were disclosed in news reports. Nor did Bush learn of a scathing classified Army report about the Abu Ghraib abuses, which was completed in February, until news organizations reported on it this week, the spokesman said.
Tom Daschle, the Democratic leader in the Senate, demanded to know why Bush had not been told earlier about the report.
"Why, in other words, has there been this extraordinary disconnect, this unbelievable failure of communication, of oversight?" Daschle said.
Army officials said they were doing all they could to handle the widening allegations of abuse.
"We take maltreatment of detainees very seriously," said Gen. George Casey, vice chief of staff of the Army, after disclosing the additional investigations. "We are completely committed to getting to the bottom of this and holding accountable those who we find guilty."
Lawmakers pressed Casey and other Army officials in the secret briefings about the training of soldiers at the prison and the role of civilian contractors, as well as flaws in the chain of command that might have contributed to the scandal.
"This is as serious a problem of a breakdown in discipline as I've ever observed," Warner said.
Defense officials should have told Congress about the case in January, when they began investigating, "but here we are in May," Warner said.
Sen. John McCain, an Arizona Republican, said Congress should investigate "why there wasn't better oversight" of those alleged to have committed the abuses.
A classified Army report obtained by The Sun found that two military intelligence officers and two civilian contractors were "directly or indirectly responsible" for the mistreatment of prisoners at Abu Ghraib.
McCain complained that the Pentagon had left lawmakers "completely in the dark" about the abuse cases. He criticized Pentagon officials for not informing members of the Armed Services Committee earlier of "an issue of this magnitude."
Sen. Carl Levin of Michigan, the senior Democrat on the Armed Services panel, said Congress should conduct a full investigation into the allegations to see how widespread they are.
One senior Democrat and leading critic of the Bush administration's Iraq policies, Sen. Edward M. Kennedy of Massachusetts, said he believed the alleged abuses were part of a pervasive pattern of detainee mistreatment by the U.S. military.
"This does not appear to be an isolated incident," Kennedy said after the secret briefing, calling the allegations involving Abu Ghraib "the beginning rather than the end" of revelations of misconduct at prisons in Iraq, as well as detention centers in Afghanistan and Guantanamo Bay in Cuba.
But on the other side of the Capitol, the Republican chairman of the Armed Services Committee, Rep. Duncan Hunter of California, said that "six idiots" were entirely responsible for abuses at the Abu Ghraib prison outside of Baghdad, and there is "no evidence" that military intelligence officers, civilian contractors or other superiors were culpable.
Rep. Roscoe G. Bartlett, whose Western Maryland district is home to the 372nd, expressed concern that the six accused reservists were being presumed guilty and said the roles of their superiors should be scrutinized.
Besides the criminal investigation of the 372nd, there are 20 other investigations going on, Maj. Gen. Donald Ryder, the Army's provost marshal, said.
Ten of those involve prisoner deaths; 10 others involve assaults, including one sexual assault, officials said. The investigations, which date from December 2002, involve some cases from Afghanistan but mostly from Iraq.
In addition, investigations involving 15 other prisoner cases, all involving death, have been completed, officials said. Twelve of those deaths were found to have been from natural or undetermined causes; another was considered justifiable homicide, involving a prison break at Abu Ghraib, officials said.
The other two cases were classified as homicides. One involved an Army guard who shot a detainee at a detention center in September after the detainee threw rocks at him. The soldier was court-martialed, reduced in rank and discharged from the Army.
The other case, which occurred in November, involved a CIA contractor working at Abu Ghraib. The case was turned over to U.S. government prosecutors because the Army has no jurisdiction, officials said.
A CIA official said the agency's inspector general was looking into two deaths involving Iraqis, one at Abu Ghraib, the other elsewhere in Iraq.
Meanwhile, officials said that Brig. Gen. Janis Karpinski, who commanded the 800th Military Police Brigade, to which the 372nd was attached in Iraq, was expected to be relieved of her brigade command soon.
Karpinski has already received a letter of admonishment by the Army's ground commander in Iraq, Lt. Gen. Ricardo Sanchez, for "serious deficiencies" in her brigade, according to the classified Army report, written by Maj. Gen. Antonio M. Taguba.
Karpinski and soldiers from the 372nd have complained that members of the 205th Military Intelligence Brigade, who were responsible for conducting the interrogations at the prison, told them to "soften up" the detainees. An Army investigation is looking into the conduct of the interrogations and the role of military intelligence personnel and civilian contractors.
One officer cited for wrongdoing in the Taguba report, Col. Thomas M. Pappas, commander of the 205th based in Wiesbaden, Germany, is still in command, officials said yesterday. The Taguba report recommended that Pappas receive a reprimand for failing to ensure that his soldiers followed proper procedures and were instructed in the Geneva Conventions on treatment of prisoners.
Officials said additional criminal charges might be filed against one or more soldiers of the 372nd Military Police Company.