Shaker Aamer, the last British man in Guantanamo Bay, is to sue British intelligence services for alleged torture and unlawful detention at the Cuban base.
His lawyers will take that case to the Investigatory Powers Tribunal - alleging that MI5 and MI6 made defamatory statements about him which led to his imprisonment without trial.
Saudi Arabian national Aamer, whose wife is British-born, has been detained in the controversial prison camp for 11 years and has has been cleared for release by both the Obama and Bush administration, but never freed.
Aamer was arrested in 2001, after 9/11, in Afghanistan, where the US have alleged he was fighting for Al Qaeda.
Aamer has said he was working there for a Saudi charity, and that British intelligence services provided "false information" to his interrogators when he was sent to Guantanamo.
The complaint filed alleges that “the actions of the [UK] security services [which] have prevented [his] release due to defamatory statements that have no basis in honest fact.”
It also alleges mistreatment by UK security services at Bagram prison in Afghanistan, where he was interrogated, “despite the fact that they knew that [he] was being abused,” and “actively sanctioned or encouraged [his] illegal transfer from Afghanistan to Guantánamo Bay.”
Lawyers at Reprieve, representing Aamer, say they believe false information was provided by British intelligence is leading to his ongoing detention at Guantanamo – in contradiction with the publicly-stated policy of the British Government.
Reprieve Legal Director, Kat Craig said: “The US has cleared Shaker, and the British Government wants him home – so why is he still there? All the evidence points to briefing against him by the UK intelligence services, who are terrified that his release will allow him to speak freely about the part they played in his torture and rendition.
"In effect, our spies are undermining the aims of our democratically elected Government. The IPT will be worthless if it cannot put an end to this scandal.”
Shaker’s four British children – the youngest of whom he has never met - and British wife all live in South London. The family arrived in Britain in 1996 and were granted indefinite leave to remain.
The IPT, which hears complaints about MI5, MI6, tGCHQ and misuse of surveillance powers, hears most of its evidence in closed session, with the complaint rarely allowed to hear evidence used by security services to make their cases.