Acclaimed director Michael Winterbottom ("A Cock and Bull Story", "24 Hour Party People", "Welcome to Sarajevo") had been showing the film at the Berlin Film Festival, where it has won a number of top awards.

"The Road to Guantanamo" traces the true story of Shafiq Rasul, Asif Iqbal and Ruhal Ahmed, three Muslim friends from Birmingham who were picked up as aliens in Afghanistan by US forces and ended up in Guantanamo for three years, where they suffered brutal and humiliating treatment.

Extensive interrogation established that they had no connection with al-Qaida, and despite their plight being ignored by British authorities, eventually they were returned home. The UK media covered live the return of these "Suspected terrorists" and the massive police convoy that brought them in to Ventral London for questioning. Their release after the UK police also found they had no connection with terrorism was, naturally, hardly mentioned.

Last week the three ex-detainees travelled to the Berlin Festival with the Winterbottom party, and were arrested yesterday under the Prevention of Terrorism Act as they returned with the Winterbottom Party. They were held by Special Branch and questioned for several hours about where they had been and who they had met. They were also questioned on Michael Winterbottom's politics.

Even more worrying, the three actors who portrayed them in the film were also arrested and questioned. The actors have no particular political or religious affiliation and were also arrested apparently purely on the basis that they were Asian. None of the white members of the group were arrested.

Following legal intervention by Gareth Peirce, the group were eventually released. Special Branch claimed they had not been arrested, merely detained under the Prevention of Terrorism Act.

On Saturday the party will be returning to Berlin again to accept the film's awards. We wait to see what will happen when they come home this time.

"The Road to Guantanamo" will premiere on Channel 4 on 9 March.

If you are concerned about this latest abuse of "anti-terrorism" powers, please write to your MP free of charge via the website www.writetothem.com.

UPDATE - Craig Murray says:

"On both www.craigmurray.co.uk and Blairwatch people have been questioning my source for this, and particularly querying why it is not in the mainstream media if it is true.

Well, I was in Winterbottom’s office yesterday, and heard it first hand, from people who were there when it happened. Nowadays the real news isn’t in the mainstream media, I am afraid. Leave them to their celebrity stories, and if you want to know what’s important, come to the web."