Admiral Stansfield Turner, who was in charge of the Central Intelligence Agency (CIA) during the 1970s, said Dick Cheney was overseeing torture policies of possible terrorist suspects and was damaging America's reputation by doing so.

President George Bush and other leading members of the his administration have consistently denied that detainees suspected of belonging to al Qaida were tortured for information.

But his opponents and human rights campaigners have claimed that many men taken captive in Iraq and Afghanistan by the US have been subjected to torture in order to extract information.

Speaking on ITV news Admiral Turner said: "We have crossed the line into dangerous territory.

"I am embarrassed that the USA has a vice president for torture. I think it is just reprehensible."

He added: "He (Mr Cheney) advocates torture, what else is it? I just don't understand how a man in that position can take such a stance."

Republican Senator John McCain has passed a provision to a defence Bill in the senate banning "cruel, inhuman or degrading treatment" of all US detainees.

But the White House has apparently threatened to veto the measure if it is passed by the House of Representatives.