By Naresh Puri and Dominic Casciani
BBC News home affairs team
Jamil Rahman: Legal action launched
A British man who has accused the government of collusion in his alleged torture in Bangladesh has spoken for the first time.
Jamil Rahman, who is suing the Home office, says he believes MI5 were responsible for his arrest in 2005.
He claims Bangladeshi officers beat him and threatened to rape his wife if he did not confess to being a terrorist.
The BBC cannot verify the claims; the Home Office says it will respond with vigour to any action Mr Rahman brings.
The British government says it does not condone torture or its use abroad.
In his first interview since launching a legal action against the government, Mr Rahman told the BBC that he was arrested in Bangladesh in December 2005 by the DGFI intelligence agency.
The former civil servant from south Wales had emigrated earlier that year to marry.
Mr Rahman said he believed that two MI5 officers directed his arrest and were aware that he was subsequently subjected to physical and mental abuse.
He was initially held for three weeks before being released. His alleged mistreatment continued at sporadic interviews for another two years.
Speaking for the first time about the alleged abuse, Mr Rahman said that Bangladeshi officers assaulted him after he was taken to an interrogation centre.
"They stripped me naked and said that if I didn't say what they wanted me to say, they would rape me and my wife and burn her and other family members.
"They told me to say I was al-Qaeda and the organiser of the 7/7 [London suicide] bombings."
It was all to do with the British ... Even the Bengali intelligence officer told me that they didn't know anything about me, that they were only doing this for the British
The 31-year-old told the BBC that two British men would question him separately. He later concluded they were the same balaclava-wearing men to whom Bangladeshi officers turned to for orders during his arrest.
"The first time [they interviewed me] they tried to be friendly, they came in trying to show they were my friends, calm and relaxed, nothing wrong. I tried to demonstrate my innocence - I thought this is wrong, because they were British I might get some justice.
"But they just said 'they had not done a good job on you' we need a ten minute break. The DGFI guys would take me to a room and beat me."
Mr Rahman says that he was questioned about bomb plots and shown scores of surveillance pictures taken in the UK.
"They were questioning me on the July 7 bombings, showing me pictures of the bombers. I didn't even know who they were. They showed me hundreds of pictures. Black, white, Chinese, bearded non-bearded, woman, man, young and old. Every time, they came for a new session, same pictures with new ones.
"They showed me maps, terrains of Bangladesh, Pakistan, Afghanistan, UK, they asked me to draw things out and write names next to pictures.
"The main thing they wanted me to be is a witness against another British man in Bangladesh. They pressured me so much to be a witness against this guy in court.
We firmly reject any suggestion that we torture people or ask others to do so on our behalf - Mr Rahman has made a lot of unsubstantiated allegations.
"They threatened my family. [The MI5 officers] they go to me: 'In the UK, gas leaks happen, if your family house had a gas leak and everyone got burnt, there's no problems, we can do that easily.
"It was all to do with the British," he said. "Even the Bengali intelligence officer told me that they didn't know anything about me, that they were only doing this for the British."
Mr Rahman admits that he attended meetings in the UK of the radical Islamist group, al-Muhajiroun, but that he rejected their ideology before his emigration for marriage.
In a statement, the Home Office said it would respond vigorously to any action that Mr Rahman brings.
"We firmly reject any suggestion that we torture people or ask others to do so on our behalf. Mr Rahman has made a lot of unsubstantiated allegations. They have not been evidenced in any court of law."
The Bangladeshi government has not answered BBC requests for a response to Mr Rahman's allegations.
At least seven former detainees are now alleging British collusion in their mistreatment abroad. Their cases list 19 alleged officers - although it's not clear whether they are all separate people because of the use of pseudonyms.
BBC home affairs correspondent Daniel Sandford said the allegations went against what security service personnel would be taught.
"Those who are familiar with MI5's techniques say the whole point about the way MI5 works is they try to build a rapport with people," he said.
"If people think you're involved in their torture then how are you going to get any information out of them that you can rely on?"
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