Former terrorist suspects who were held in CIA prisons and tortured have been given the green light to sue the two men who devised the “enhanced interrogation” programme - marking the first time the US government has allowed a civil case against the CIA to proceed.

Judge Justin Quackenbush, a federal judge in Spokane, Washington state, ruled that the case against James Mitchell and John "Bruce" Jessen, two CIA contractors, could proceed.

The pair, both former Air Force psychologists who had no experience of al-Qaeda, devised a programme for the CIA that drew from 1960s experiments involving dogs, and a theory called "learned helplessness."

The interrogation programme is now widely discredited following a 2014 Senate report, which found that the methods used were not successful. The report said sleep deprivation, waterboarding and beatings had inflicted pain on al-Qaeda prisoners far beyond the legal limits, and yet did not result in important, lifesaving intelligence.

The case against the two psychologists has been brought by the American Civil Liberties Union on behalf of three men, none of whom were ever linked to al-Qaeda.

Suleiman Abdullah Salim, a fisherman from Tanzania, and Mohamed Ahmed Ben Soud, a Libyan exile from Gaddafi’s regime, were held in CIA prisons but never charged with crimes and are now free.