The families of two senior RUC officers murdered in an IRA ambush have appealed to An Garda Síochána and the PSNI to co-operate closely and overcome the apparent distrust between them.

The call was made this evening at the conclusion of evidence by Detective Chief Superintendant Peter Kirwan at the Smithwick Tribunal - during which it emerged there were deep divisions between the two senior intelligence officers.

The Tribunal is investigating claims of garda collusion in the murder of RUC Chief Supt Harry Breen and Supt Bob Buchanan in March 1989.

Last October ACC Harris told the Tribunal that current "live" intelligence they had obtained revealed that a senior PIRA member said he had several gardaí including those of a senior rank – inspector or above - who passed information to them.

ACC Harris confirmed the PSNI had an ongoing investigation into that allegation.

Other intelligence said that the IRA “traditionally obtained extremely good intelligence from Dundalk Garda Station” and that a garda had passed information to the IRA which led to the ambush in which Lord Justice and Lady Gibson were killed in 1987.

All this intelligence was graded “reliable and accurate” according to ACC Harris.

Today Chief Supt Kirwan was cross examined by Mark Robinson, Counsel for the PSNI, and he cast doubt over the PSNI assessment saying it had “many glaring omissions”.

It was, he added, “amazing” that all this intelligence had emerged decades after the crimes when nothing like it had been heard in the aftermath of the killings.

He also said he was unable to give a detailed assessment of this latest intelligence because, contrary to usual practice, it had not been shared with the gardaí.

Chief Supt Kirwan pointed out that at an EU meeting, ACC Harris had stressed the importance of sharing intelligence between police forces but that had not happened in this case.

Mr Robinson, on behalf of the PSNI, pointed out that it was their priority to protect the sources of intelligence.

This material had come from multiple sources, been assessed and graded as 'reliable and accurate'.

However, the witness said he could see no reason why the PSNI would not share the intelligence which could have a major impact on the Garda Síochána.

It was usual for the two forces to share intelligence, he added.

It was put to him that ACC Harris actually had first hand information about the sources of the allegations but the witness repeated his assertion that he was not convinced.

Mr Robinson also put it to the garda intelligence chief that he had accepted what the IRA had said in statements but had rejected everything the PSNI had said.

However, Chief Supt Kirwan said he resented the idea that he was a “self-interested witness”.

Details in the IRA statement could be checked, the allegations in the PSNI intelligence could not, he said

The Tribunal is investigating claims of garda collusion in the murder of RUC officers, Chief Superintendent Harry Breen and Superintendent Bob Buchanan in March 1989.

They were killed in an IRA ambush just minutes after leaving a meeting in Dundalk Garda Station.

Three former garda sergeants, Owen Corrigan, Leo Colton and Finbarr Hickey have all been questioned at the Smithwick Tribunal regarding the allegation and all three have strenuously denied involvement.