The Pentagon plans to transfer about a dozen inmates of the Guantanamo Bay military prison in Cuba to at least two countries, a US official has said.
The first of the transfers were expected in the next few days and the others in the coming weeks, said the official on Wednesday who spoke on condition of anonymity.
The transfers are part of President Barack Obama's latest push to close down the facility, which opened the US to accusations of torture.
Tariq Ba Odah, a Yemeni man who has been on a long-term hunger strike and has lost about half of his body weight, will be among the prisoners being transferred.
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Ba Odah's lawyers had tried unsuccessfully to win his release on health and humanitarian grounds, but Pentagon officials said he was receiving proper care.
There are now 91 prisoners at the Guantanamo Bay prison. Most have been held without charge or trial for more than a decade, drawing international condemnation.
Obama, who last month presented Congress with a blueprint for closing the prison, faces stiff opposition from Republicans as well as some from his fellow Democrats.
The administration wants to avoid fuelling any political outcry over specific sites during a US presidential election year.
The Pentagon has notified Congress of its latest planned transfers from among the 37 detainees already cleared to be sent to their homelands or other countries.
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"I do not have a timeline on when particular detainees will be transferred from Guantanamo," Commander Gary Ross, a defence department spokesman, said in a statement.
"However, the administration is committed to reducing the detainee population and to closing the detention facility responsibly," Ross added.
Guantanamo prisoners were rounded up overseas when the US became involved in wars in Iraq and Afghanistan following the September 11, 2001 attacks on New York and Washington.
Former US President George W Bush opened the facility, which came to symbolise aggressive detention practices.