At the same time Mr. McCormack flagged a potentially contentious issue: what restrictions are to be placed on the detainees if they are returned to Britain.  Before releasing any detainees, the United States wants assurances they “would be secured, meaning that they wouldn’t be allowed to walk free,” Mr. McCormack said.  In its statement today, the British Foreign Office said that if the men were returned, they would be subject to the same security considerations “as would apply to any other foreign national in this country.”  In the past, British officials have said, in court documents that have largely gone unnoticed publicly, that Britain could not agree to the conditions sought by the United States because they would violate British and European human rights laws and would require an onerous commitment of British intelligence resources.  The British move Tuesday was greeted with great jubilation by human rights groups and campaigners for the closure of the prison camp at Guantánamo.  “It’s brilliant news,” said Asim Qureshi, spokesman for Cageprisoners, a nonprofit organization that works on behalf of Guantánamo detainees. “We’re really happy today.”  Clive Stafford Smith, who represents the five men, said the British move was “a sign that the new Brown Administration recognizes that human rights are important in the battle against terrorism.”  Gordon Brown replaced Mr. Blair as Prime Minister in June. A change in the British policy had been a matter of intense debate within the Labor Party during the last months of Mr. Blair’s tenure. It is not clear whether Mr. Blair would have approved of the shift had he remained in office.  Nine British citizens were released from Guantánamo in 2004 and 2005. The Bush administration had expected the men to be tried and incarcerated for some period and was dismayed when they were allowed to go free. Several have gone on to become near celebrities here.  One of the five men on the list Britain submitted on Tuesday, Jamil el-Banna, was authorized to leave Guantánamo by the American military authorities in May, but is still being held because the British would not take him. Mr. el-Banna was seized by the C.I.A. in Gambia, where he had gone on a business trip. British intelligence agencies had been monitoring Mr. el-Banna because of his ties to Islamic radicals here and had alerted the C.I.A. of his travel to Gambia. But it had specifically requested that he not be arrested, according to a recent British government report.  The others whose release the British government sought today are Shaker Aamer, Omar Deghayes, Binyam Mohamed and Abdennur Sameur.  Several Bush administration officials said that particular scrutiny would be given to two of the detainees in the British request, Mr. Aamer and Mr. Mohamed. The officials said these two men were considered more serious threats than the others.  A Pentagon spokesman, Cmdr. J. D. Gordon, said conditions set by the United States for the release of any Guantánamo detainee to a host government include providing “credible assurances that they will be treated humanely” and guarantees “that the countries will take steps to mitigate the threat that these individuals pose to the United States and its allies.”  Commander Gordon said that 420 Guantánamo detainees have been released and that only 38 of those were determined to be “no longer enemy combatants.”  He said that about 80 more detainees have been cleared for departure from Guantánamo “and will be transferred once humane treatment and continuing threat concerns have been satisfactorily addressed by the receiving country.”  The State Department’s deputy spokesman, Tom Casey, said the British and American governments had been discussing the fate of these five detainees “for some time.”  “We certainly don’t, as the president said, want to be the world’s jailer, and we don’t want to see Guantánamo Bay open indefinitely,” Mr. Casey added. “But in order to be able to close it, you have to have a way of dealing with the people that are there, many of whom are extremely dangerous individuals, and those that will require some continued supervision and monitoring.”  Mr. Casey said the British request would be evaluated, “and I’m sure we’ll be having a number of discussions over the next few weeks to see” how the transfer could be handled.  Among the five detainees, Mr. Mohamed is a gangly Ethiopian who had lived in Washington for two years as a teenager, before his family moved to Britain. He was seized in Pakistan in April 2002 and turned over to the Americans. His was one of the early cases of rendition, the Bush administration policy of secretly taking suspected terrorists to third countries for interrogation.  Mr. Mohamed was taken to Morocco, where he was held and interrogated for 18 months, according to Mr. Stafford Smith. According to the accounts he gave to his lawyer, Mr. Stafford Smith, and which have been published elsewhere, he was brutally abused there. On several occasions, men used a scalpel to make cuts on his penis, Mr. Mohamed has alleged.  American officials initially said that he was an accomplice with Jose Padilla in a plot to detonate a dirty bomb in the United States. That charge was eventually dropped against Mr. Padilla, who is on trial in Miami on other terrorism-related charges. Mr. Mohamed has not been formally charged.  Mr. Deghayes, who moved to Britain from Libya in 1986, after his father, a union organizer was assassinated, was seized in Pakistan in January 2002. He has been held in Guantánamo as “enemy combatant,” and military officials have alleged that he traveled from Pakistan to Afghanistan under the guidance of Al Qaeda, and that he had a good relationship with Osama bin Laden.  The American evidence against him also included a photo allegedly of him in Chechnya. At Mr. Deghaye’s administrative review board hearing in 2005, he generally denied links to Al Qaeda, and introduced testimony from a expert that the person in the photo was not of Mr. Deghayes, but of another Chechnya fighter.  Mr. Deghayes has been a leader of the hunger strikers at Guantánamo, as has Mr. Aamer, a native of Saudi Arabia,who wears his hair pulled back in a pony tail. American officials said he had ties to Al Qaeda, which he denied.  The fifth detainee on the list, Mr. Sameur, is an Algerian, who fled the country in 1999 and was granted political asylum in Britain. In 2001, he went to Afghanistan, where American officials have alleged he trained at an Al Qaeda camp, which he denies. He fled Afghanistan in October 2002 and was picked up by the Pakistani army and turned over to the Americans.  The British Foreign Office said that discussions between the United States and Britain about the release of these four men “may take some time.”  One sticking point in the past has been the conditions that the United States has sought to have imposed on any detainees returned to Britain.  It wants the men jailed for some period, and then upon their release to be subjected to control orders and closely monitored, including communications intercepts, according to statements by the director-general for intelligence at the Foreign Office, David Richmond, and by the director of counterterrorism at the Home Office, William Nye. They were filed last year in a case brought by two detainees on the current list, Mr. Deghayes and Mr. El Banna, who were seeking to force the government to act to secure their release.  Such measures would be illegal, the British officials said.  Mr. Nye added that measures used by Britain against terrorist suspects, including interception of communications, human intelligence resources, “and other intelligence-gathering and analytical techniques” would not satisfy the United States.  “None of these techniques, individually or collectively, would be able to provide the sort of guarantee sought by the U.S.,” Mr. Nye said.  A compromise may be found, with the released men voluntarily agreeing to some restrictions.  “We’d be willing to submit to any reasonable restrictions,” said Mr. Stafford Smith, the lawyer.  A British detainee released earlier this year, Bisher al-Rawi, voluntarily agreed to register with the police, notify them of any change of address for 5 years, to report to the police one a month, and report to the police any plans to travel outside Britain for five years, according to documents in the case.  He was not forced to give up his passport, which is something else the Bush administration has sought.  Thom Shanker contributed reporting from Washington.
The request, a major policy reversal for Britain, is likely to be welcomed by the Bush administration, which has been working to reduce the number of detainees.