A senior garda officer has said there were "significant persuasive elements" in the IRA's account of how they planned and set up an ambush in which two senior RUC officers were murdered in March 1989.
Detective Chief Superintendent Peter Kirwan, the head of the Security and Intelligence section of An Garda Síochána, was responding to claims the IRA had made during meetings with members of the legal team from the Smithwick Tribunal.
They said they carried out the operation after surveillance of Dundalk Garda Station, which was done with no help from any garda mole.
The tribunal is examining claims that the IRA received information from a garda which allowed them set up the ambush in which Chief Superintendent Harry Breen and Superintendent Bob Buchanan were killed in 1989.
The senior garda officer was also critical of the PSNI.
He said information presented to the tribunal by them was insufficient for the gardaí to investigate the allegations.
They had written to the PSNI and MI5 seeking more information but got no response, he said.
He was responding to evidence given by Assistant Chief Constable Drew Harris, who said the PSNI had current intelligence alleging a senior member of the IRA had several gardaí who passed information to him - including a senior officer.
It was also claimed that the IRA got "good intelligence" from Dundalk Garda Station and that a member of the force passed information to the IRA which allowed them kill Lord and Lady Gibson in a car bomb back in 1987.
Solicitors for the families of the RUC men expressed serious concern about what they had heard.
John McBurney and Ernie Waterworth said it was very regrettable to hear a senior garda say the intelligence had not been properly shared.
"Clearly this needs very urgent attention to allow the Garda Commissioner fully investigate the PSNI intelligence," they said.
Det Chief Supt Kirwan was critical of the intelligence put before the tribunal by the PSNI, saying they had not been given enough information to examine the claims.
He said he was not convinced all the relevant factors had been considered in examining the information by the PSNI.
It was put to him by senior counsel for the tribunal, Mary Laverty, that the "elephant in the room" was that ACC Harris was prevented from giving any more details about the intelligence.
The witness replied that he was not in a position to comment on the idea.
Earlier, he said the gardaí had been given the intelligence in a very brief summary - the same summary presented to the tribunal to be made public.
He stated that the gardaí had not been given access to more detailed information about it.
The Garda Chief stated they had not been given "even half a chance" to interpreting what the intelligence actually means.
He had written to the PSNI about the matter and another letter was then written "at a more senior level" but did not say if they got a response.
Ms Laverty also pointed out that the tribunal was told by the PSNI they would not be getting access to the background intelligence documents because it was too sensitive.
However, the garda chief said he held ACC Harris as a professional officer of the highest standard.
He also spoke about the close co-operation that normally exists between the PSNI, British security forces and the gardaí.
