WASHINGTON (AFP) - Congressional leaders agreed for the first time Wednesday that Guantanamo detainees could be sent to US soil for trial, boosting President Barack Obamas bid to close the prison. In two different draft bills, key Democratic lawmakers added clauses that would authorize detainees at the US naval base in Guantanamo Bay, Cuba to be transferred to the United States to face trial under strict conditions. But they did not address whether the Obama administration can hold prisoners indefinitely without charge in the United States or what the fate would be of those who may be acquitted after trial. Both draft texts explicitly barred any of the 223 detainees still in Guantanamo from being freed in the United States-an issue now before the Supreme Court. Democratic senators and congressmen added language to a Department of Homeland Security appropriations bill that prohibits detainees from being transferred to the US except to be prosecuted. Such transfers would only be allowed after Congress receives a plan detailing the risks involved, how to mitigate them and other demands. A less specific clause added to a Defense Department authorization bill demands that the president provide a comprehensive disposition plan at least 45 days prior to any transfer of detainees to the United States. The measures must still face a vote before the full Senate and House of Representatives. Just last week, the House voted to prevent the transfer of Guantanamo detainees to the United States for any reason. Underscoring his partys position, Republican Representative Hal Rogers said he still had serious concerns over allowing Guantanamo Bay detainees to come to the US for purposes of prosecution. Some prominent Republicans, including Senator John McCain, have supported closing the facility which has attracted widespread condemnation. Of those still held at the controversial prison camp, about 80 are waiting to be released and a further 60 are expected to be prosecuted. Obama has ordered the jail shuttered by January 22, but W House officials have admitted they may not meet the deadline as they encounter numerous setbacks to the plans. The govt team tasked with assessing the detainee cases has also struggled to persuade other countries to take some of the captives, with only a trickle of prisoners-some 27 transferred since Obamas inauguration in January. The principle promoted by Republicans and a number of Democrats of no terrorists in my backyard, even if the detainees were contained alongside mass murderers and rapists in high security federal prisons, has become a rallying cry for some politicians ahead of the 2010 mid-term elections. US prisons already house a number of inmates suspected or convicted on terror charges, such as Al-Qaeda plotter Zacarias Moussaoui, the only person convicted in the attacks of September 11, 2001, who is serving a life sentence in Colorado. A third group of inmates beyond those awaiting release or prosecution remains the trickiest to deal with as they are deemed too dangerous for release and cannot be tried in US court because the evidence against them is possibly tainted by abuse or contains sensitive intelligence. Observers warn these prisoners may eventually be held indefinitely without trial in the United States. Labeling Guantanamo an icon of injustice, Jameel Jaffer of the American Civil Liberties Union said Congress should be supporting rather than interfering with efforts to close it. A system that allows indefinite detention without charge or trial has no place in a democracy, added Jaffer, who heads the rights groups National Security Project. On the military commissions system for prosecuting terror suspects held at Guantanamo, Senate Armed Services Committee chairman Carl Levin said the defense bill would preclude the use of coerced testimony and place greater limits on the use of hearsay evidence. Defendants would also be provided with better access to witnesses and documentary evidence, as well as representation and resources. More than 550 detainees have been transferred from Guantanamo since it was opened by former president George W. Bush in January 2002, according to the Defense Department.