Media caption Raymond Gilmour says he has been left unable to work and in fear for his life

However, he said he was provided with modest accommodation and £600 a month for three years and was not provided with employment. He also said his false identity does not stand up to scrutiny.

He also claims to have suffered alcoholism and post-traumatic stress disorder (PTSD) as a result of his work and has been left destitute.

With the assistance of his MP, who the BBC has decided not to name, he is now taking his case to the Investigatory Powers Tribunal (IPT) - a body which examines complaints against the intelligence services.

Liam Clarke, Belfast Telegraph political editor I would imagine, given this publicity, the security services will probably want to do somethinghe joined the Irish National Liberation Army (INLA) in 1976 as a Royal Ulster Constabulary (RUC) special branch agent.

'Saved countless lives'

He said he then moved to the IRA in 1980 before his cover was blown two years later when police used information he supplied to recover a machine gun.

"I brought the INLA to their knees in Derry, I brought the IRA to their knees in Derry and I saved countless lives," he said.

"If I'm being treated like this after so many years, what do you think people down the chain are being treated like?

"I am living on a knife edge because of my mental health, I have no financial stability, which I was promised - I have nothing."

His decision to testify in the early 1980s led to the