By Nick Childs
BBC Pentagon correspondent
US Attorney General John Ashcroft says he is not aware of President Bush giving any order that would violate laws banning torture of prisoners.
The prisoner abuse scandal has overshadowed Mr Bush's Iraq policy
This came after leaks suggesting that government lawyers had advised that the president could override such laws.
The Iraq prisoner abuse scandal continues to expose raw political nerves in Washington.
The latest evidence of this came in tense questioning in the Senate of the attorney general.
The Bush administration rejects torture, Mr Ashcroft insisted.
Mr Ashcroft angered senators by saying he would not hand over a memo in which reports said government lawyers had advised the president he could override laws on prisoner treatment.
It was clear from the questioning in the Senate that critics of the administration see the leaks as further evidence that it encouraged the climate which led to the prisoner abuses in Iraq.
The administration rejects the charge. The memo was used in a draft report last year that was part of a Pentagon review of interrogation policy at the Guantanamo Bay detention centre.
The Pentagon acknowledges using interrogation methods at Guantanamo Bay which have gone beyond previous military practice.
But it insists they are humane and within international law and that the more extreme proposals were rejected.