David Cameron has said there should be a full inquiry into allegations that British security officials have been complicit in torture.
Speaking in the Commons, the Conservative leader called on the prime minister to deal with Binyam Mohamed's "serious allegation".
And he argued that Gordon Brown must be satisfied that Britain had acted with "moral authority" in the case.
"This government unreservedly condemns the use of torture," Brown replied.
"I have instructed that where allegations are made, they should be looked at by the courts."
And he noted that the attorney general was looking specifically at Mohamed's case, while the intelligence and security committee would examine the issue of rendition in detail.
"I have made it clear that there is a next stage [to this investigation]," the prime minister added.
Dods Parliamentary Communications Ltd