David Davis said a High Court ruling on Wednesday alleged that Binyam Mohamed, a UK resident held in the Guantanamo Bay camp in Cuba, had been tortured.
The judges also said the US threatened to withdraw intelligence help from the UK if details were released.
But Foreign Secretary David Miliband said there had been no such threat and the UK "never condoned torture".
"There has been no threat from the US to break off intelligence co-operation," he said.
He stressed that the US-UK security relationship was built on trust and that depended on intelligence remaining confidential. The judges said the UK's attorney general has begun a criminal investigation into possible torture against Mr Mohamed.
