|Obama's plan for Guantanamo Bay has been undermined by a string of measures by supporters of the prison [EPA]
The US House of Representives have approved legislation that will block the transfer of prisoners from Guantanamo Bay to face trial in criminal courts on the US mainland.
If approved by the Senate after its endorsment by the House on Wednesday, the move will be a setback to President Barack Obama's plan to close the military jail at Guantanamo Bay by prosecuting or releasing the men being held there.
The law works by preventing the White House from spending any money on transferring the prisoners to US soil, effectively derailing plans to try them in civilian courts.
In the past, detainees, including Khalid Sheikh Mohamed, the self declared mastermind of the September 11 attacks, have been sent to the US to face trial.
The provision was buried in essential legislation that authorises funding for the government's operations to the end of the 2011 financial year.
The planned law has drawn criticism from the White House, which says Congress has no right to interfere with the administration's plans to prosecute Guantanamo prisoners.
"We strongly oppose this provision. Congress should not limit the tools available to the executive branch in bringing terrorists to justice and advancing our national security interests," a Justice Department spokesman said.
If the provision is approved by the Senate, it will ensure that Obama's plans to close Guantanamo are further delayed, as there will be no prospect of many of the 174 prisoners being held there being transferred before the end of September 2011.
The move is the latest in a string of measures by supporters of Guantanamo that have thwarted Obama's pledge to close the prison. The White House is seeking to bring the prisoners into a recognised judicial system after almost a decade spent in legal limbo.
Republicans are opposed to the idea, and say that inmates should be tried at Guantanamo by specially convened tribunals. Their opposition deepened when the first Guantanamo prisoner to be tried in the US was acquitted on 299 of 300 terrorism charges against him.
The Obama administration points out that civilian courts have prosecuted hundreds of terrorism cases in the past, and sees no reason why Guantanamo prisoners should be treated any differently.