The Bush administration's policies for holding and detaining suspected terrorists came under sharp scrutiny and criticism yesterday after disclosure that the CIA had set up covert prisons in several Eastern European democracies and other countries.

The U.N. special rapporteur on torture said he would seek more information about the covert prisons, referred to in classified documents as "black sites." Congressional Democrats and human rights groups warned that the secret system would damage the U.S. image overseas.

House Democrats said they plan to introduce a motion as early as today to endorse language in the defense spending package written by Sen. John McCain (R-Ariz.), which would bar cruel and inhuman treatment of prisoners in U.S. custody, including those in CIA hands. The motion would instruct House conferees to accept McCain's precise measure.

Rep. John P. Murtha (Pa.), ranking Democrat on the Appropriations defense subcommittee, urged the United States to adopt a doctrine of "no torture, no excuses," and said Congress needs to speak on the issue. "The United States of America and the values we reflect abhor human rights violators and uphold human rights," Murtha said in a statement.

McCain's amendment was endorsed last month by the Senate, 90 to 9, over the objections of the White House, which said it would restrict the president's ability to protect the country. The House Democrats said they already have 15 GOP supporters for their motion, and Republicans have told the White House they expect it to pass, an Appropriations Committee spokesman said.

The CIA and the White House are seeking language that would exempt prisoners held by the agency, which would include the 30 or so al Qaeda figures that sources said are being held in the black sites. Neither the White House nor the CIA will officially comment on the secret prison system, but intelligence officials have said in interviews that the arrangement is essential to gaining information about possible terrorist activities.

The Washington Post reported Wednesday that the CIA's covert detention system has at times established facilities in eight countries, including, among others, Thailand, Afghanistan and Guantanamo Bay, Cuba. Those facilities are now closed. The Post did not publish the names of Eastern European countries involved in the program, at the request of senior U.S. officials. They argued that doing so could damage counterterrorism efforts in those countries and elsewhere, and could lead to retaliation by terrorists.

The governments of Russia and Bulgaria issued statements saying no such facility existed in their countries, Reuters reported. Thailand also denied hosting such a facility.

Yesterday, administration officials were buffeted by questions about the black sites.

"The fact that they are secret, assuming there are such sites, does not mean" torture would be tolerated there, national security adviser Stephen J. Hadley told reporters.

"Some people say that the test of your principles [is] what you do when no one's looking," he said. "And the president has insisted that whether it is in the public or it is in the private, the same principles will apply and the same principles will be respected. And to the extent people do not meet up, measure up to those principles, there will be accountability and responsibility."

State Department spokesman Sean McCormack also declined to talk specifically about the sites, saying, "These are difficult issues. And we have ongoing discussions on a variety of different fronts with countries around the world about these issues, because the threat from terrorism . . . is a common threat to democracies and peace-loving nations."

Human rights groups said the al Qaeda prisoners should be brought to trial, rather than held indefinitely in covert prisons in which they have no recognized legal rights. "We think these people should be prosecuted and punished fully for the murders of thousands of people," said Tom Malinowski of Human Rights Watch. "What is really clear is that this is a dead-end policy and they are close to the dead end."

John D. Rockefeller IV (D-W.Va.), vice chairman of the Senate Select Committee on Intelligence, has been pushing for more than a year to conduct a review of the CIA's interrogation and detention practices. Yesterday, he lashed out at the administration for not being more forthcoming.

"They have made it clear that anyone who suggests that oversight is needed should be labeled as unpatriotic," he said.

Manfred Nowak, the U.N. special rapporteur on torture and other cruel, inhuman or degrading treatment or punishment, said he had heard allegations of secret detention facilities sponsored by the United States, but had not heard of any in Eastern Europe before yesterday.

"Every secret place of detention is usually a higher risk for ill treatment, that's the danger of secrecy," Nowak said in a telephone interview from Austria, adding that he wants to pursue access to all U.S. detention facilities outside its territory.

Nowak and his predecessor have been trying to gain access to the U.S. military detention facility at Guantanamo Bay since it opened in early 2002.

Last week, the Bush administration invited U.N. experts to Guantanamo but offered a one-day visit with no ability to talk to detainees. Nowak said he would not accept because a "guided tour" would not allow him to probe allegations of abuse.

"I have many allegations that detainees have been abused while in Guantanamo," he said. "If I didn't have plenty of allegations, I wouldn't bother the United States government with trying to visit."

A senior U.S. official, speaking anonymously yesterday, said the administration is unlikely to budge: "The offer they have is the final offer. We are not prepared to open Guantanamo up to just anyone who wants to come in and talk to detainees."

Staff writers R. Jeffrey Smith and Jonathan Weisman and researcher Julie Tate contributed to this report.