In a diplomatic breakthrough that is likely to help the Obama administration close the Guantánamo detention camp, Portugal said this week that it was willing to resettle some detainees and urged other European countries to accept prisoners remaining at the camp, which has been a source of international criticism for nearly seven years.
The announcement was the first sign in the tangled history of the detention center in Guantánamo Bay, Cuba, that other countries might be willing to accept the Bush administration's assertion that they should play a role in shutting it down.
"The time has come for the European Union to step forward," Portugal's foreign minister, Luís Amado, said in a letter to other European ministers released Thursday.
"We should send a clear signal of our willingness to help the U.S. government in that regard, namely through the resettlement of detainees," the letter said. Mr. Amado pledged that Portugal would participate in a European Union resettlement program.
Although there is no specific agreement yet on the transfer of detainees, Bush administration officials described the announcement as a critical step toward solving the problem that has been referred to as "Guantánamo's hard cases." That refers to some 60 of the remaining 250 detainees whom the Pentagon has cleared for release but who cannot be sent to their home countries, often out of concern that they would be tortured or persecuted. They are from countries including Algeria, China, Libya and Tunisia.
"This is a major milestone in our efforts to secure help from the international community, and particularly from Europe, in closing Guantánamo," said John B. Bellinger III, the State Department's legal adviser.
Human rights groups and detainees' lawyers welcomed the announcement, saying it could pave the way for the shuttering of Guantánamo in the early months of the new administration. "This step is an important one to usher us into a new era," said Emi MacLean, a staff lawyer at the Center for Constitutional Rights, which represents detainees and has worked on the resettlement issue.
Mr. Bellinger said that Albania was the only country that had accepted detainees who were not its own former residents, when it accepted five Uighur detainees originally from western China in 2006. The State Department has been working for five years to persuade other countries to take some of the detainees who are in limbo because no country that the United States finds acceptable is willing to take them.
One obstacle has been resistance of some American officials to permitting detainees to be resettled in the United States.
Diplomats said the announcement by Portugal was partly a product of personal diplomacy by Secretary of State Condoleezza Rice during a trip in September. But they said it also appeared that the logjam was breaking because other countries were eager to show the incoming Obama administration that they were willing to assist in the complex challenges of closing the camp.
If the 60 "hard cases" were resettled, the challenge of closing Guantánamo would be considerably diminished. About 100 of the remaining detainees are Yemenis, and American officials have long been working separately to get Yemen to promise to provide security assurances, monitoring and retraining so that many of the Yemeni detainees could be repatriated.
Resettlement programs in Europe and Yemen would leave about 100 detainees. With that smaller number, some officials say, it would be easier to close Guantánamo and transfer the remaining detainees to prisons in the United States.
President-elect Barack Obama has said he will close Guantánamo but has provided few details. He has suggested that some prisoners could be prosecuted in federal courts. Those men could be held in federal or military prisons. But the Obama transition office has not offered details of where the remainder might be held.
Mr. Bellinger said Portugal had received no promises of any assistance from American officials in exchange for its announcement.
But he described the announcement as a sign of a shift in attitudes in other capitals. "We kept telling them," he said, "it's fundamentally unfair to keep criticizing Guantánamo while doing nothing to help."
In an interview, Luís Serradas Tavares, the legal adviser in the Portuguese Foreign Ministry, said his government was trying to lead the way toward a solution to what he called "a U.S. problem."
Mr. Tavares said the details of a resettlement program would need to be worked out but might include some type of monitoring, like parole after a criminal conviction. But he said receiving governments would agree to free detainees cleared for release by the Pentagon.
He said he expected Portuguese people to be anxious about accepting men held at Guantánamo who the Bush administration said were dangerous.
But he said, "The U.S. has assured us that these people are the least dangerous people."