Allegations and denials
According to a new report from UN Human Rights Council, British security and intelligence officers were often present when British citizens suspected of terrorism, were interrogated by foreign powers.
But the British government denies the allegations, saying they are unsubstantiated and irresponsible.
One of the people named in the report is the British resident Omar Deghayes. He went to university in the UK and qualified as a lawyer before travelling to Afghanistan in 1999. When the American attack on Afghanistan began, Omar took his family to Pakistan where he was arrested as a suspected terrorist.
After a spell in detention at the Bagram airbase in Kabul, Omar was taken to Guantanamo Bay where he was held for six years.
Omar says he was repeatedly tortured and beaten and lost the sight in one eye after an attack by a guard.
Now along with other British prisoners, he is taking the UK government to court, seeking to establish their involvement in his ordeal.
Omar describes his experiences to Matthew Bannister and tells him why campaigning for the remaining Guantanamo detainees to be freed is helping him readjust to life in the UK.