Leading article: Britain and Europe must stand by their principles

The British political establishment has been demonstrating a disgracefully equivocal attitude on the subject of torture for some time. The head of MI5, Eliza Manningham-Buller, openly admitted in a recent statement to the Law Lords that her organisation makes use of the testimony of terror suspects who have been tortured abroad. And Jack Straw, speaking on behalf of the Government in the past, has articulated a similarly flexible attitude. The Foreign Secretary has argued that, if information that could stop a terrorist attack were received it could not be ignored, no matter how it was extracted. The line from those charged with safeguarding out security appears to be: "We do not condone torture, but we are happy to receive any information that results from it."

But now we learn that our government has sunk even lower into this immoral quagmire than we previously imagined. It has been alleged that the CIA has been using UK military and civilian airports as a stop-off point in the transportation of terror suspects en route to torture chambers abroad. This is surely more than turning a blind eye to the repugnant practice of torture. If these allegations are true, our government is actively facilitating it.

Of course, we have no way of knowing for certain at this stage which individuals have been processed through UK airports by the CIA, nor their ultimate destination. That information is never likely to be freely divulged by the US. But we know enough about the workings of the Bush administration to make an educated guess. The CIA admits that it has been operating a policy of "rendition" in which prisoners are transferred to friendly states such as Egypt and Jordan for questioning. These are countries known to use torture routinely. There is also evidence that the CIA has established secret prisons in Eastern Europe. What goes on in these places is unknown. But testimony from suspects that have subsequently been released points to torture.

Our government has so far been evasive on this subject. It claims it is not aware of British land being used for suspect flights abroad, but admits that records of transit applications have, for some unspecified reason, not been kept. It also refuses to confirm or deny the existence of secret US prisons in third countries. It is to be hoped that the new all-party group of MPs that will meet next week to press the Government on this subject will succeed in getting some answers.

It is, of course, no mystery why the Bush administration is behaving like this. Detaining suspects on foreign soil means they are unable to contest their imprisonment in the US courts. It also means they can be interrogated over a long period. It is a cynical way of getting round the law. But the duty of our government is clear: the US must be denied access to our airspace for any flight in which terror detainees are being rendered to third countries or secret prisons. Britain must also back the robust stance of the EU Justice Minister, Franco Frattini, in calling to account any member state that allows the US to run covert detention centres on its territory.

The manner in which the United States has disregarded the human rights of terror suspects since the 11 September attacks has disgraced that nation's good name. Transporting detainees for questioning in dubious third countries is little more than torture by proxy. And to the scandals of Guantanamo Bay and Abu Ghraib we must now add the so-called "black sites" in Romania and Poland.

Torture - no matter how "light" - cannot be justified on any grounds. It is not too late for Britain to stand up to its ally and refuse to have any part in this vile practice whatsoever.