Michael Mukasey, Bush's attorney general, angered Democrats and some Republicans when he repeatedly refused to answer the question of whether waterboarding was torture during his 2007 confirmation hearing.

Holder also pledged that the US prison facility in Guantanamo Bay, Cuba, would be closed but said it would take longer than expected by some rights groups, who condmned the treatment of detainees at the facility.

His comments came a day after a top US official reportedly said Mohammed al-Qahtani, a Saudi Arabian national held at the US prison facility in Guantanamo Bay, Cuba, had been tortured and she had recommended he not be prosecuted as a result.

Meanwhile Hillary Clinton, Obama's former rival for the Democratic presidential nomination and pick for secretary of state in his cabinet, was approved by the senate foreign relations committee on Thursday.

Clinton still has to be officially nominated and then confirmed by the full senate but this is expected to be a formality conducted after Obama's inauguration on January 20.

'Legal' tactics

Last year the US Central Intelligence Agency (CIA) admitted it had used waterboarding on three al-Qaeda suspects at Guantanamo Bay including Khalid Sheikh Mohammed, the alleged mastermind of the September 11 attacks in 2001.

The Bush administration, which has said US interrogators do not currently use waterboarding, maintains that all interrogation tactics currently in use are legal.

However Susan Crawford, a Bush administration official in charge of deciding whether to bring detainees to trial, said the techniques used on al-Qahtani were "abusive and uncalled for" and that therefore she could not recommend he be prosecuted.