The Smithwick Tribunal has gone into closed session after it was announced that the PSNI has significant new and current intelligence relating to garda collusion.
At the resumption of tribunal hearings this morning, it emerged that the PSNI had 12 new pieces of intelligence that are being put before the tribunal by Assistant Chief Constable Drew Harris.
Following an application by the PSNI, Judge Smithwick agreed that as the intelligence was new and current it should be heard in private.
In July, the PSNI produced five other pieces of intelligence, some of which claimed that another garda, who is not before the tribunal, had passed information to the IRA.
Depending on the value the judge places on this new intelligence, today's development could make it difficult for the tribunal to meet the deadline of 31 October.
The Smithwick Tribunal was set up to investigate claims that a garda passed information to the IRA, which led to the ambush and deaths of two senior RUC officers in March 1989.
Chief Superintendent Harry Breen and Superintendent Bob Buchanan died just minutes after leaving a meeting in Dundalk Garda Station.
Three former garda sergeants, Finbarr Hickey, Owen Corrigan and Leo Colton, have all denied passing the information to the IRA that led to the ambush.
The tribunal has been investigating the claims for seven years. It began public hearings last year.
Today is the first day of public sittings by the tribunal in six weeks.
Counsel for the tribunal Mary Laverty said the PSNI had come forward with intelligence "that had manifested itself quite recently" as a result of investigations.
She said the information was highly sensitive and as such they had no objection if the material was to be heard in private.
However, counsel for Owen Corrigan, Jim O'Callaghan, said the tribunal has been placed "in an impossible position by the PSNI and the British Security Services who make decisions whether or not intelligence is disclosed".
He pointed out that a previous PSNI officer who had attended the tribunal had said it had presented all the intelligence it had. Then he had come back in July with further information and now again the PSNI was presenting even more intelligence.
PSNI not cooperating - O'Callaghan
Mr O'Callaghan said it was clear that the PSNI was not co-operating with the tribunal.
James McGuill, who represents Mr Hickey, said it appeared to him that the PSNI had "sat on their hands" for the entire tribunal and had now started producing this information.
It seemed to him that the judge would have to embark on an entire re-hearing of the evidence because documents were withheld.
Ms Laverty said that it would have been easy for the PSNI to sit on its hands, but to say that it had been withholding information was not correct.
Diarmaid McGuinness, counsel for the Garda Commissioner, said it was very difficult to effectively cross-examine if information is only brought before the tribunal today.
He wondered if ACC Harris would also account for how it had "misled the tribunal" and its previous silence in relation to the intelligence that they brought forward in July and again today.
Mark Robinson, for the PSNI, said the Chief Constable was taking the work of the tribunal very seriously and would be keen for ACC Harris to return for cross-examination if necessary.
Regarding the intelligence to be given today, it was current and highly sensitive and on that basis it needed to be given in private.
The founder and chairman of a victims group based in south Armagh has claimed that material linked to IRA attacks went missing from Dundalk Garda Station.
Frazer denies Red Hand Commando claim
Willie Frazer, who is involved with Families Acting for Innocent Relatives (FAIR), denied at the tribunal a claim that he was a member of the loyalist group, the Red Hand Commando.
That allegation had been made by former Det Garda Sergeant Corrigan during his evidence to the tribunal.
Mr Frazer said today in the witness box that it was not true and it was a lie regularly put out by the IRA.
He also claimed material and cars that had been linked to IRA terrorist attacks simply went missing from Dundalk Garda Station over the years.
The tribunal has adjourned until next Tuesday when it will resume hearing evidence from ACC Harris in private about the new intelligence.
The judge also said he would be expecting an update on the health of Mr Corrigan on that day.