The INLA man who shot dead the LVF leader, Billy Wright, inside the Maze prison in 1997, claims the British authorities "turned a blind eye" to the killing.
Mr Christopher McWilliams also claims authorities in the North were fully aware of the INLA plot to murder Wright inside the prison.
Mr McWilliams made the allegations during an interview for tonight's BBC 2 Newsnight programme.
The interview will form part of an overall feature on Wright's murder.
The allegations by Mr McWilliams are certain to prompt renewed calls for an independent, public inquiry into the circumstances of the prison murder on December 27th, 1997.
Wright's father, Mr David Wright, who has always claimed his son's killing was "state-sponsored, state-orchestrated and state-sanctioned", said Mr McWilliams's remarks were "a damning indictment" of the Prison Service and the Northern Ireland Office.