Chris Mullin: America must tell us the truth about its gulag

In his book Decent Interval, about the final days of the Vietnam war, the former CIA agent Frank Snepp told of the fate of a high-level Communist prisoner, Nguyen Van Tai. "Just before the North Vietnamese tanks rolled into Saigon, a senior CIA official suggested it would be better if he disappeared ... The South Vietnamese agreed. Tai was loaded into a plane and thrown out at 10,000ft over the South China Sea. At that point, he had spent over four years in solitary confinement, in a snow-white room, without ever having fully admitted who he was."

There is nothing new about the CIA being involved in torture and unexplained disappearances. What is new is that since 9/11, and perhaps before, a secret American gulag appears to have been created with a global network of detention and interrogation facilities into which prisoners disappear. Sometimes they are heard of again, sometimes not. Occasionally, they die. Most of the "disappeared" are undoubtedly involved to a greater or lesser extent in terrorism. Some appear to be victims of mistaken identity.

Evidence about this gulag has emerged only gradually. Survivors have begun to surface. There are verifiable reports of America's prisoners being "loaned" to interrogators in a growing list of countries where torture is endemic, including Egypt, Libya, Morocco and Syria.

This gulag is serviced by a fleet of jets registered to CIA front companies circling the globe, shuttling prisoners between Europe, the US and the Middle East. Thanks to assiduous plane-spotters, we know these aircraft are frequent visitors to British airports. Whether they are merely passing through or whether they are carrying human cargo we cannot say for sure. On occasion, two planes have landed simultaneously at the same British airport, suggesting some sort of transfer between them.

Where does Her Majesty's government stand? There is no evidence that British ministers or officials are complicit. The worst they can be accused of is a disappointing lack of curiosity but, as the questions multiply, there is such a thing as wilful ignorance and it seems we are close to that point. Fortunately, some of our European partners are showing greater curiosity. At their urging, our Foreign Secretary Jack Straw, as EU president, has had to write to his US opposite number, Condi Rice, asking for an explanation.

We should not hold our breath. In due course, he will be in receipt of a carefully drafted response which will not take us a lot further. The question will then arise, what do we do next? The obvious step is to detain and search the next suspect plane that appears on our soil. That is what we would do if we had evidence drugs were being smuggled, so why not when we have a reasonable suspicion they may contain kidnap victims or victims of torture? But a search is unlikely to yield much of interest. The Americans know they have been rumbled and will reroute their planes through countries less squeamish. That will not be a reason for dropping the subject. We must insist we are told the truth.

It is not enough to protest, as government spokesmen have, that we do not support torture. We must demonstrate that we do not by actions as well as words. Not to do so is to risk allowing ourselves to be reduced to the moral low ground occupied by the very terrorists we are fighting. That would be a victory for terrorism, if ever there was.

Chris Mullin is a former Foreign Office minister and a member of the all-party group on extraordinary rendition