The Smithwick Tribunal went into private session after a former intelligence officer with the RUC said that no agents of the State "recruited at that time" were involved in the murder of two senior RUC officers.
Known as Witness 62, the former RUC Special Branch officer, made his comment while being cross examined Dermot McGuinness, senior counsel for the Garda Commissioner this afternoon.
The Tribunal is investigating claims that an IRA mole within the gardaí tipped them off about a meeting involving two senior RUC officers in Dundalk Garda Station in March 1989 allowing them time to set up the ambush in which they were killed.
Witness 62 and Mr McGuinness were discussing the role of Peter Keeley who is also known as Kevin Fulton. Mr Keeley had claimed he was recruited by the British army to work undercover in the IRA. However, Witness 62 disputed the value of Mr Keeley.
The witness dismissed claims by Mr Keeley that the two RUC officers, Chief Supt Harry Breen and Supt Bob Buchanan, were killed by British agents in the IRA unit to prevent them being taken alive and giving details of informants.
He said that was just nonsense. The witness said that when people like Mr Keeley started to run out of useful things to pass on, they just made up information.
The witness earlier stated that no agents of the State were involved in the murders. He later went on to say there were no agents of the State "or anyone who was recruited at that time was involved in the shooting."
After making his comments, Mark Robinson, counsel for the PSNI requested the public and media be excluded and the Tribunal continue in private session. Judge Smithwick acceded to the request.
After about 15 minutes of private evidence, the Tribunal resumed hearing evidence in public.
The former intelligence officer also said he had a conversation with a garda about former Det Sgt Owen Corrigan who was being named by RUC colleagues as someone who had passed information to the IRA.
Witness 62 said there was an embarrassed nod and an acceptance there was a problem although he acknowledged that could have been related to other problems, not necessarily that he was an IRA mole.
He had told the Tribunal earlier that it was very, very difficult to sometimes get evidence to get someone removed. He had instances where people were passing information to UDA, UVF or IRA. They had good intelligence but not evidence that would stand up in a court of law.
He was also asked what he took from a comment made by a garda officer when they were discussing Mr Corrigan "don't be so hasty there's another boy". The witness said he took that to mean there was another member of the force involved in passing information to the IRA.
The Tribunal is investigating whether Mr Corrigan, retired sergeant Leo Colton or former sergeant Finbarr Hickey passed information to the IRA which helped them set up the ambush.
All three have vehemently denied the accusation.
Earlier, the witness had said there was major infighting among members of the IRA in South Armagh following the murder of a family who were killed in a case of mistaken identity.
Builder Robert Hanna, his wife Maureen and their seven-year-old son David died when their car was blown apart by the 1,000lb pound bomb detonated by the IRA in July 1988 at Killeen, just north of the border on the main Dublin to Belfast road. They were returning home from a holiday in America.
The intended target was High Court Judge Eoin Higgins and his family who were also driving home to Belfast after a holiday in America.
Witness 62 said there was major fallout within PIRA as a result of the attack. Some members were outraged at what had gone on while others just accepted it as part of the war.
The witness said there were fights in bars between IRA members as a result of the attack.
Witness 62 earlier spoke in detail about the Provisional IRA in the border areas.
He said the ambush was carried out by members of the North Louth/Dromintee brigade of the PIRA assisted by others from Crossmaglen and other units.
He said he did not want to praise terrorists but the North Louth/Dromintee unit were highly efficient, very formidable and very experienced. They were very cautious and would not mount an operation like this ambush without good intelligence.
They were involved in many murders of RUC officers, as well as Judge Gibson and his wife, and the Hanna family.
The North Louth/Dromintee PIRA unit was led by Sean Gerard Hughes, he said.
Thomas 'Slab' Murphy was a more senior member of the IRA. He was on the army council and was chief of staff of the IRA.
He also revealed the Special Branch had an informal system of grading members of the IRA.
They were either A, B or C team members.
The A were the top, most professional while the C team would have only have been used once or twice a year to act as a look-out or dig a bomb in.
Regarding the ambush in which the two RUC officers were killed, Witness 62 said that he had never come across such a large scale operation mounted in daylight with up to 25 men taking part.
It involved committing many men and resources to one attack and, he said, it would have taken considerable pre-planning organising the volunteers, weapons and transport.
He said it would have taken at least two hours to get the operation up and running, but that the logistics would have been done earlier.
The witness also said he was told some years after that there was an IRA member on the main road and alerted the ambush team that the RUC officers had turned off and were driving up the Edenappa Road.
Whatever route the RUC men had taken they were going to be attacked, he said.