Sinn Fein has called for an independent inquiry into allegations by a convicted loyalist gunrunner, Lindsay Robb, that RUC officers colluded with loyalist paramilitaries to jail a high-profile republican for the killing of a former UDR soldier.
Robb, who was part of a PUP talks delegation that had discussions with the British government before the 1994 loyalist ceasefire, claims RUC Special Branch officers struck a deal with loyalists to send a prominent Lurgan republican, Mr Colin Duffy, to prison for the murder of a former UDR soldier, John Lyness, in 1993.
According to Robb, the plot to jail Mr Duffy was hatched when RUC officers approached the UVF following the Lyness murder and asked them to supply a "clean witness" with no direct terrorist links. The witness would then claim to have seen Mr Duffy in the vicinity of the Lyness shooting.
Robb says he was approached by senior UVF commanders and instructed to testify against Mr Duffy, who was subsequently jailed for life.
After the court case, Robb was issued with a personal protection weapon, a 9mm Walther pistol. He claims he was also given £2,000 "by way of a thank-you from the RUC".
"My evidence against Duffy was part of a deal struck with loyalist terrorists, namely the UVF, and the RUC," said Robb. "Initially I didn't want to give evidence. However, when the RUC approached the UVF and asked for help in dealing with Duffy, I agreed.
"Those who approached the UVF were RUC Special Branch officers. I told the RUC that I wasn't going to do this for nothing, and that's why I was given the gun and the money."
Following Robb's revelations, a Sinn Fein Assembly member, Dr Dara O'Hagan, said: "We are looking at proof positive from a man linked to a loyalist terrorist organisation that collusion was going on."
Dr O'Hagan and the party's spokesman on policing, Mr Gerry Kelly, both called for an immediate, comprehensive, independent inquiry to be set up to investigate Robb's allegations. The party also intends to raise the matter with Amnesty International.
Yesterday the RUC denied that any of the CID officers involved in the Lyness murder made contact with the UVF. An RUC spokesman said: "Robb was a witness in the trial. Following the murder he was identified by a telephone call made by him to police. His involvement is a matter of court record. The CID investigating team did not ask the UVF for assistance during the murder investigation."
Mr Duffy's sentence was later quashed following Robb's conviction in 1995 of conspiring to acquire arms and ammunition for the UVF.
Robb left prison last year on early release. He now lives in Scotland.