A senior US official has welcomed Portugal's offer to take in some of the inmates from the detention centre at Guantanamo Bay.
John Bellinger, the legal advisor to US Secretary of State Condoleezza Rice, described the move as 'a significant step'.
He said it was the first break in a European-wide refusal to help Washington close the centre. Mr Bellinger said the US needed the help of Europe in order to shut the centre down.
Portugal's offer, made public in a letter by its foreign minister Luis Amado, is too late to help the Bush administration but it could make it easier for US President-elect Barack Obama to close the remote prison that is viewed widely as a stain on the country's human rights record.
'This is extraordinarily significant,' Mr Bellinger told wire services. 'It is the first time that any country except Albania has privately or publicly stated that they are prepared to resettle Guantanamo detainees who are not their own nationals.
'It really is a first crack in the ice of what has been European opposition to helping with Guantanamo in any way. For five or six years there has been consistent criticism but no constructive offers to help,' he said.
'Growing recognition of problem in Europe'
The Portuguese offer is timed to help Sen Obama fulfil his pledge to close Guantanamo Bay and Bush administration officials said Mr Amado also wanted to indicate a recent narrowing of legal differences between Washington and Europe over the issue.
Mr Amado said in his letter to European partners it was time to show Sen Obama's incoming government a clear willingness to resettle prisoners and thereby help to close the detention centre.
'The time has come for the European Union to step forward,' said the letter, released on Thursday.
Guantanamo Bay was opened in January 2002 to house terrorism suspects caught in US President George W Bush's war against terrorism. It came under strong criticism immediately for confining hundreds of suspects without charge, ultimately for years, and has badly damaged US credibility on human rights issues.
Mr Bush has said he would like to close the prison before his term ends on 20 January but officials say a host of legal and practical problems prevent that, despite efforts in recent months to send detainees to their home countries.
About 250 men remain imprisoned there, including 50 the US has cleared for release but cannot repatriate for fear they will be tortured or persecuted back home.
Mr Bellinger and other senior US officials have been crisscrossing Europe and other regions in the past year trying to get countries to take in detainees.
While en route to Libya last September, Ms Rice stopped in Portugal to discuss the issue and Mr Bellinger said it was evident Mr Amado wanted to help.
Mr Amado did not make clear in his letter which detainees his country would be prepared to take in and Mr Bellinger said no agreement had been drawn up with Lisbon on how to proceed. 'There is not a specific deal,' he said.
But Mr Bellinger said there appeared to be a recognition among some in Europe that Guantanamo was no longer just a US problem but an international issue that needed to be resolved.
'Europe needs to stop simply calling for its closure but to step up and actually help with its closure,' he said.
Of particular concern is what will happen to those detainees deemed too dangerous to be released, Mr Bellinger said.
In addition, more than a third of the prisoners left are from Yemen and the State Department still has not been able to reach a deal with that country on either security assurances or guarantees that prisoners would be treated humanely.
'There will be hard decisions to make,' Mr Bellinger said of the challenge facing Sen Obama.
Mr Bellinger said it could take some time before Guantanamo Bay was completely shuttered and many issues needed to be resolved, including the possible transfer of some detainees onto American soil, which is unpopular among most communities.
'The reason it has not been closed was not through lack of trying,' he said. 'The new administration will find that there are many practical and legal difficulties.'
