Leon Panetta, the director of the CIA, said during his confirmation hearings earlier this year that he would not permit the rendition of detainees to foreign countries for the purpose of torture.

Panetta said Obama had banned "that kind of extraordinary rendition - when we send someone for the purpose of torture or actions by another country that violate our human values".

"I do not believe we ought to use renditions for the purpose of sending people to 'black sites' [secret prisons in other countries] and not providing the kind of oversight I believe is necessary," he said.

But he said some kinds of renditions of prisoners were "appropriate".

"I think renditions where we return individuals to another country where they prosecute them under their laws, I think that is an appropriate use of rendition," Panetta said in February

'No protection'

"It is extremely disappointing that the Obama administration is continuing the Bush administration practice of relying on diplomatic assurances, which have been proven completely ineffective in preventing torture"

Amrit Singh, American Civil Liberties Union

But rights groups say diplomatic assurances on the humane treatment of suspects will not protect them against abuse.

"It is extremely disappointing that the Obama administration is continuing the Bush administration practice of relying on diplomatic assurances, which have been proven completely ineffective in preventing torture," Amrit Singh of the American Civil Liberties Union, told the New York Times.

Singh, tracked rendition cases under George Bush, Obama's predecessor, cited the case of Maher Arar, a Syrian-born Canadian citizen sent by the US to Syria in 2002.

He was given assurances against torture but was found to have been repeatedly beaten with electrical cables.

The Obama administration's decision to continue so-called renditions is based on a series of recommendations proposed by a taskforce the president set up days after taking office in January, to review rendition and interrogation tactics employed by the US.

The task force proposed improved monitoring of treatment of prisoners sent to other countries, but Singh said the usual method of such monitoring - visits from American or allied consular officials - had been ineffective.