Former Guantánamo detainee says his campaign against state complicity in torture and rendition is real reason for move

The former Guantánamo Bay inmate Moazzam Begg has been stripped of his UK passport after visiting Syria.

Begg, 45, from Birmingham, says he was stopped by police at Heathrow airport on his return from a trip to South Africa and told that his passport was being confiscated as it was "not in the public interest" for him to travel.

A Home Office order given to him at that time stated that he had been assessed as being involved in terrorist activity because of a visit to Syria last year, while the police are reported to have said that royal prerogative powers were being used to confiscate the passport.

Begg denied any involvement in terrorist activity, however, and said he was being harassed because of his work with Cageprisoners, a London-based Muslim NGO that campaigns for the rights of individuals detained during counterterrorism operations. He told the Mail on Sunday: "I have consistently been asking for the intelligence and security services to be held to account for complicity in torture and rendition. It is more logical that is the reason I've had my passport confiscated."

A Home Office spokesperson said: "We do not routinely comment on individual cases.

"The royal prerogative power provides an important tool to disrupt individuals who seek to travel on a British passport to engage in terrorism-related or other serious criminal activity abroad which impacts on the UK. The decision to refuse or withdraw a passport in the public interest must be proportionate and will only be used sparingly."

Begg spent almost three years detained without trial after being seized in Pakistan in early 2002, spending most of this time at Guantánamo. He is one of several British men who sued the British government for damages over their detention in Guantánamo. The government settled out of court after being compelled to hand over documents that showed that British government ministers had decided that a number of British Muslims should be consigned to the US-run prison, despite being aware that they faced being mistreated.

Last week an official inquiry reported that there was evidence that British intelligence officers had been involved in the abuse of some of these men.