Former IRA members have claimed there was no Garda involvement in the murder of two senior RUC officers.
Provisionals told a tribunal that Chief Superintendent Harry Breen and Superintendent Bob Buchanan were under surveillance for almost a year before they were killed in an ambush.
The Smithwick Tribunal is investigating allegations that three former members of An Garda Siochana passed information to the IRA which led to the killing of the men, shortly after they left Dundalk Garda Station in March 1989.
The three ex-officers deny collusion.
In an unsigned statement to tribunal staff, three PIRA members said armed units were instructed to intercept the unmarked police car and arrest the pair. "The car was put in reverse and attempted to escape. At that point the RUC detectives were executed," it said.
The information was disclosed as Taoiseach Enda Kenny hit out at former Provos for refusing to give evidence in person at the inquiry. Sinn Fein leader Gerry Adams described the assistance the IRA gave to the tribunal as "historically unparalleled".
Tribunal chairman Judge Peter Smithwick agreed to have the evidence read into the record after investigators cut ties with the three former IRA members who refused to give evidence in person or be cross-examined over a video link.
The Provos - referred to as A, B and C - said the ambush was down to painstaking surveillance and accused Mr Buchanan, who drove the RUC car, of being sloppy and a creature of habit.
They insisted the murder plot was carried out by a unit from south Armagh and rejected suggestions that either the south Down IRA or Peter Keeley, a British agent who infiltrated the terror group in the Newry area and used the pseudonym Kevin Fulton, would have known about the operation. They also denied claims of collusion from anyone in Dundalk Garda Station, including former Detective Sergeant Owen Corrigan, who they described as "hostile to the IRA".
"This operation had no help from anyone in the Garda," they said. "This was a classic surveillance, hard, dogged work, there was no help from anyone at all."