Senior US lawmakers say they have reached a compromise deal that eases restrictions on sending Guantanamo detainees home or to third countries but bars their transfer to the United States.
The deal could set up a potential first step toward closing the controversial prison, a campaign pledge made by President Barack Obama back in 2008.
The bipartisan agreement reached by two senators and two House of Representatives members still requires passage by both chambers as part of a sweeping defence spending bill.
Democrat Carl Levin, chairman of the Senate Armed Services Committee who helped craft the deal, said he hoped the overall bill would pass this month, with the Guantanamo provisions intact.
The deal includes Senate language "easing restrictions on overseas transfers of GITMO detainees but it retains the House prohibitions on transferring detainees to the United States," Levin said.
Cumbersome and complicated procedures have forced some detainees to remain in Guantanamo long after they have been cleared for transfer home, reinforcing the argument that the prison is acting as a recruiting tool for militant groups.
Levin said the plan would "give flexibility to the president to transfer detainees from Guantanamo to third countries".
Easing restrictions could allow about half the detainees eligible for transfer to their home countries or elsewhere, with the other half, including 9/11 suspects, remaining at Guantanamo.
Republican House Armed Services Committee chairman Buck McKeon said the two parties "found common ground" in their deal.
"Our plan is to bring it to the floor this week, get it passed, send it to the Senate," he said.
Some rights groups said the plan was crucial in Obama's longstanding bid to close the prison.
"The proposed defence bill is the first step toward untangling the knot that is Guantanamo," Human Rights First said in a statement.
"It provides a path forward for foreign transfers that balances our security interests and our legal obligations."
But Amnesty International USA described the agreement as "one step forward and one step back".
While welcoming the easing of transfers abroad, the group's executive director Steven Hawkins said "the House's restriction on transfers to the US, even for trial or medical treatment, is a terrible blow for human rights.
"President Obama must find a solution to end the Guantanamo crisis," he added.
US officials sent two Guantanamo detainees home to Algeria last week, reducing the number of detainees at the prison to 162, including 82 cleared for transfer.
