BRITISH security service MI5 provided the intelligence which proved to be a key factor in the Smithwick Tribunal deciding that there had been garda collusion in the murders of two senior RUC officers.
The intelligence, which was described as "live and of the moment", was presented in private session to the tribunal by PSNI Assistant Chief Constable Drew Harris.
It is understood that the critical information viewed by Judge Peter Smithwick was collected by MI5 agents during surveillance of veteran republicans operating in the border region.
The intelligence included a document which stated that the Provisional IRA had received information from an unnamed garda mole, who had not
been before the tribunal, about the movements of the officers, Chief Supt Harry Breen and Supt Bob Buchanan.
But the claims were strongly challenged by a senior counsel for Garda Commissioner Martin Callinan in his closing statement to the tribunal last June and he dismissed the allegations as not merely nonsense but "nonsense on stilts".
The garda authorities were particularly incensed at the late introduction of "fresh" intelligence.
However, in his findings, Judge Peter Smithwick indicated that he accepted the thrust of the intelligence, despite the garda objections.
Commissioner Callinan said yesterday that what had taken place at the tribunal did not affect the current day-to-day co-operation between the two police forces and the sometimes hourly sharing of intelligence.
He said he regarded Drew Harris as a true friend and valued his judgment in terms of their intelligence-sharing.
In relation to the tribunal, Mr Callinan said the PSNI had one position and An Garda Siochana had another.
The commissioner said he accepted the tribunal's findings and apologised for any failings by the gardai. He was horrified by the conclusion that a garda had betrayed the force by colluding with the Provisional IRA.
It was beyond comprehension that any member of his force would engage in collusion with the IRA and betray the force to that degree.
Mr Callinan said it was a source of great disappointment that no one had been held accountable for the two murders and that first and foremost his thoughts were with the families and loved ones of the two officers.
He described the Provisional IRA as a terrorist organisation and said that for a garda to collude with them was an act of betrayal.
Mr Callinan pointed out that when the RUC officers were murdered in 1989 they were dark times for the country and the IRA was then at its height, with victims being killed on both sides of the Border.
But he disputed the claim by Judge Smithwick that there was a culture in An Garda Siochana in which loyalty was more prized than honesty.
"I have to say that the police force described in the report is not the police force that I lead. Everything we do in An Garda Siochana is designed to establish the truth. That is our raison d'etre and that will continue to be the case."
Mr Callinan said the garda authorities had delivered any piece of documentation that was of use to the tribunal and none had been redacted.
He expected his members to be loyal to the force, while at the same espousing the values of openness, honesty and transparency. But anyone guilty of a transgression was dealt with and he and his officers had put a number of their colleagues in jail for breaking the law.
Justice Minister Alan Shatter attacked Sinn Fein president Gerry Adams for remarks yesterday morning that the two officers had taken a "laissez faire" attitude to their own safety and said his remarks about the murders were nauseating.
He recalled that six days after the murders Mr Adams had spoken at an event in Crossmaglen in south Armagh alongside a hooded man, who sought to give an explanation for the murders. It was very unlikely, he said, that Mr Adams would have appeared beside the man unless he knew his identity.
Mr Shatter said Mr Adams had questions to answer on how he had failed to ensure that three known members of the IRA, who had been interviewed and gave their versions of what had taken place prior to the ambush to the tribunal, had not subsequently appeared as witnesses and faced cross-examination about their accounts.