Leading article: Half-truths that cloak a lawless world of depravity

At times, and these are growing more frequent, we catch a glimpse of a twilight world that seems to exist alongside our own. The world we are encouraged to believe we live in is one of sunny uplands and blue skies. It is a world governed by laws, where order prevails and politicians pledge themselves to uphold civilised values. It is one where abductions, beatings and torture are always on the wrong side of the law.

In the parallel world, things are arranged differently. Here, people are plucked off the street, held incommunicado and transported thousands of miles for questioning. It is a world of unrecorded flights in private planes that have nothing, but also everything, to do with governments. It is a world of intelligence agents who may or may not be government employees; a world where the only law is an ill-defined and ever-changing duty to ensure national security.

This week, as the season's festivities have run their course, that other world has rarely been far away. The day before yesterday, the US embassy in London "clarified" remarks made in a BBC interview by the US ambassador, Robert Tuttle. Where Mr Tuttle had said there was no evidence that terrorist suspects had been sent to Syria for questioning, he now recognised that "a media report" had spoken of just such a "rendition".

Then yesterday a Greek publication challenged a British denial of allegations that intelligence agents had been involved in the abduction, beating and interrogation of 28 Pakistanis in Greece shortly after the bombings in London. These allegations had been raised and unconditionally dismissed as "complete nonsense" by the Foreign Secretary, Jack Straw, earlier this month. Yesterday, the Foreign Office would "neither confirm nor deny" this Greek version. It did not, however, describe it as "nonsense" - complete or otherwise.

Whatever the truth of the report, the details conform to a pattern that is becoming disturbingly familiar. Allegations are made about an abduction, a prison or torture that are dismissed by ministers of the country accused - the US or Britain - as "fantastical" or "absurd". Which, of course, they are to anyone without an inkling of the parallel twilight world.

But then there emerges, if not cast-iron proof, at least evidence that makes the charges plausible. The snatched photos of the cages at Guantanamo. The photographs of prisoner abuse at Abu Ghraib. The account of the German citizen who - the US finally admitted privately to the Germans - was spirited to Afghanistan for questioning while on a private trip to the Balkans. The Canadian citizen - alluded to in the US embassy "clarification" - who was detained in the US and flown to Syria, where he says he was tortured.

What is more, a close reading of the official denials in each and every case shows that, technically, no untruths have been uttered. Thus Mr Straw, dismissing allegations about the Pakistanis in Greece, said that "no UK officials had taken part in any alleged mistreatment in Greece of any suspects ... and we were not involved in the arrest or detention of those particular suspects". Every phrase leaves a gaping loophole. In Europe last month, the US Secretary of State was as deceptively precise when pressed about "extraordinary rendition".

Others couch their denials as ignorance. Mr Blair has repeatedly failed to give a straight answer to questions about possible British government complicity. But seeing nothing, hearing nothing and saying nothing is becoming less and less of an option. We trust that, as the victims are emboldened to speak out and parliamentary inquiries multiply, the true depravity of this murky parallel world will be exposed.