The first official account of former Guantanamo Bay prisoner and Sussex resident Omar Deghayes's incarceration in US custody has emerged with the release of previously classified secret service documents.

The papers, which give details of a series of meetings between MI5 officers and Mr Deghayes in Bagram prison, Afghanistan, in the summer of 2002, suggest the Libyan-born detainee was mistreated in US custody.

A report of one such meeting, in June of that year, stated: "Deghayes was brought to the interview room manacled and hooded. When the hood was removed, Deghayes looked pale and shaky."

As confirmed by a separate document issued to British Secret Intelligence Service (SIS) operatives, for guidance on interviewing detainees, "hooding at any time" was considered "mistreatment", and expressly forbidden.

The revelation will add credence to Mr Deghayes's claim that, after being moved to the US prison camp in Guantanamo Bay later that year, he was attacked by American guards, leaving him blind in one eye.

Former Foreign Secretary David Miliband, since leaving office in May, has accepted that the US "used and condoned" torture in their network of foreign prison camps during the so-called War on Terror.

Mr Deghayes, from Saltdean, and five other former prisoners with British ties, are suing the British Government for complicity in torture. The 40-year-old was detained in Pakistan in 2002 and spent a total of five years without charge in US custody, until being released after a long campaign by supporters - backed by The Argus - in December 2007.

According to the documents, during another meeting in Bagram, in July 2002, Mr Deghayes told SIS officers he was suffering from internalbleeding, before launching into an "extended complaint" about the absence of any evidence for his incarceration.

The report, setting out Mr Deghayes's comments, continued: "He was also being treated badly, with head-braces and lock-down positions being the order of the day. He was treated better by the Pakistanis; what kind of world was is where the Americans were more barbaric than the Pakistanis?"

The papers, released to lawyers representing Mr Deghayes, also recorded the officers' belief that "Deghayes [was] clearly lying and holding backon many issues".

A spokeswoman for legal action charity Reprieve said: "These documents show that Omar was betrayed by the British government right when he needed them most. British intelligence officers apparently ignored clear signs of abuse and distress, which is both inhumane and illegal. Our government must put systems in place to ensure that this never happens again."

A spokesman for the Cabinet Office said: "The quotes mentioned are taken from a small selection of the thousands of documents that may be relevant to these proceedings. Last week the Prime Minister [David Cameron] announced an inquiry that would provide a strong and effective review of these issues."