Actors (from left) Waqar Siddiqui, Rizwan Ahmed and Arfman Usman with Michael Winterbottom and detainee Rhuhel Ahmed

The men, who play British inmates at the detention camp, were returning from the Berlin Film Festival where the movie won a Silver Bear award.

One of the actors, Rizwan Ahmed, said a police officer asked him if he intended to make any more "political" films.

The men were released quickly and not arrested, said Bedfordshire police.

Inquiry

"Six people were stopped under the Terrorism Act. This is something that happens all the time and obviously at airports and train stations," said a spokeswoman.

"There is a heightened state of security since the London bombings. Public safety is paramount."

Actor Farhad Harun was also questioned, along with Shafiq Rusul and Rhuhel Ahmed, the men whose detention in Guantanamo is chronicled in the film.

The film depicts treatment meted out at the camp

Mr Ahmed also alleges that he was verbally abused by a police officer and had his mobile phone taken from him for a short period.

The actor also claims that he was told by police that he could be held for up to 48 hours without access to a lawyer.

He says he was initially questioned at the airport's baggage pick-up area and taken to a separate room when he demanded to know why.

Human rights organisation Reprieve, who Mr Ahmed has asked to speak on his behalf, called Thursday's incident an "ugly farce".

Suspects

They have called for an urgent inquiry into what happened while one of the film's producers, Melissa Parmenter, said the detention was outrageous.

Bedfordshire police have said they will issue another statement specifically concerning the allegations made by Mr Ahmed and Reprieve.

The Road to Guantanamo, directed by British film-maker Michael Winterbottom, tells the story of the Tipton Three.

The men from the West Midlands went to Pakistan to arrange a wedding and eventually found themselves at the US camp.

They were picked up in Afghanistan and believed to be terrorist suspects and were eventually released from Guantanamo Bay in 2004 without charge.

The film, shot in Afghanistan, Pakistan and Iran, was made at a cost of £1.5m.