Tony Blair has ruled out an inquiry into claims that the CIA has used UK airports to move prisoners to third countries where they may be tortured.
Mr Blair said there was no evidence of illegal activity
He said he had no evidence to suggest that anything illegal had happened.
Mr Blair added that he did not want to "add fuel" to stories about the practice, which is known as "extraordinary rendition".
Human rights groups want an inquiry into hundreds of secret flights alleged to have passed through the UK.
The Association of Chief Police Officers has begun an investigation after receiving information about the flights from Liberty.
Foreign Secretary Jack Straw wrote to the US administration on behalf of the EU to seek clarification following reports that some of the detainees may have been flown to secret camps in former Soviet states in eastern Europe.
US former Secretary of State Colin Powell said last weekend that European governments had been aware for decades that America used rendition to transport terror suspects where traditional extradition procedures were inappropriate.
Speaking at his monthly Downing Street press conference on Wednesday, Mr Blair said: "I have absolutely no evidence to suggest that anything illegal has been happening here at all.
"I am not going to start ordering inquiries into this, that or the next thing when I have got no evidence to show whether this is right or not."
'Out of order'
He added: "All I know is that the American practice in certain circumstances, with the consent of the country concerned, of taking someone and removing them to another country or back to the US - that's a practice they have avowed, never mind admitted, for a long period of time."
Asked if he approved of rendition, Mr Blair said: "It all depends what you mean by rendition. If it is something that's illegal, I totally disapprove of it. If it is lawful, I don't disapprove of it.
"All I know is we should keep within the law at all times.
"The notion that I or the Americans or anyone else approve or condone torture or ill-treatment or degrading treatment, that's completely and totally out of order in any set of circumstances."