The US wants to ensure released inmates will be treated humanely
The US is considering a request from the British Foreign Office to release five former UK residents from Guantanamo Bay detention centre.
A senior US official said Washington would seek guarantees that the men would be treated humanely and would not be allowed to pose a security threat.
When asked whether the US considered the men dangerous, the official replied: "We believe they are."
Britain has previously not interceded on behalf of non-British citizens.
The five men are Shaker Abdur-Raheem Aamer, Jamil el-Banna, Omar Deghayes, Binyam Mohammed al Habashi and Abdulnour Sameur.
They were former UK residents who had either been granted refugee status, indefinite leave or exceptional leave to remain prior to their detention.
The United States has released individuals from Guantanamo Bay to a third country before - a group of Chinese Muslims were sent to Albania in May 2006 after the US deemed them not to be dangerous.
Those men, ethnic Uighurs, were cleared for release two years before they were freed, but the US did not send them to China for fear of persecution.
Albania was the only country willing to accept them after 20 other countries rejected them.
Abdulnour Sameur, pictured above, Algerian with leave to remain
Omar Deghayes, Libyan with refugee status
Shaker Abdur-Raheem Aamer, Saudi Arabian granted indefinite leave to remain
Jamil el-Banna, Jordanian with refugee status
Binyam Mohammed al Habashi, Ethiopian asylum seeker
The Bush Administration says the releases are in line with the stated policy of eventually closing down Guantanamo Bay.
In Washington, State Department spokesman Sean McCormack said the US would review the British request, which was "well within the confines of our policy".
"We don't want to be the world's jailers. At the same time, we also don't want to see very dangerous people allowed to walk the streets freely so they can pose a threat to our citizens as well as others," he told reporters.
Earlier UK Foreign Secretary David Miliband formally wrote to his US counterpart Condoleezza Rice with the request.
The Foreign Office said discussions on release "may take some time".
"The government will of course continue to take all necessary measures to maintain national security.
"Should these men be returned to the UK, the same security considerations and actions will apply to them as would apply to any other foreign national in this country."
The Foreign Secretary and Home Secretary said they had made the request because of recent steps taken by the US government to reduce the number of inmates at the camp in Cuba and "to move towards the closure of the detention facility".
"These steps include an increasing emphasis on engagement with third countries over the transfer and resettlement of those detained," the Foreign Office said.
The UK government said all British nationals had been released from Guantanamo Bay by January 2005.
But it had refused to act on behalf of the five men - a decision upheld by the Court of Appeal last year which agreed that requesting the return of non-British nationals would be counterproductive as the US had clearly said it would not negotiate with third countries.
"We judged that it would also have been counter-productive, at that time, to our wider aim of securing closure of the detention facility," the FCO said.
"The situation has now changed and the Foreign Secretary and Home Secretary have reviewed the government's approach in light of these circumstances."