Police on both sides of the Irish border must launch fresh investigations into the murder of two top RUC officers following intelligence reports of Garda collusion in the killings, the family of one of the men has said.
The Smithwick Inquiry was presented with the new evidence by the Police Service of Northern Ireland (PSNI) on Wednesday as the probe into the IRA killing of Chief Superintendent Harry Breen and Superintendent Bob Buchanan in 1989 draws to a close.
The police were heavily criticised for withholding the information which blamed an unnamed retired Garda officer for passing information to the killers, and not the three Garda officers who have been under scrutiny by the inquiry.
The Buchanan family said they found the withholding of the information deeply hurtful, but they asked if the delay was the fault of the Security Services in London and not the PSNI, and they said sufficient new information had come to light to warrant further criminal investigation.
"The family of the late Superintendent Bob Buchanan have taken time to reflect on the evidence presented to the Smithwick Tribunal in Dublin by Detective Chief Superintendent Roy McComb on Wednesday," they said.
"The initial reaction was one of dismay and concern that the PSNI had withheld vital intelligence material for up to seven years.
"Following this reflection the Buchanan family actually welcome the introduction of this intelligence material."
They added: "While it is not the family's intention to pre-empt the findings of Judge Smithwick it is apparent that the intelligence material produced by the PSNI, albeit late in the day, confirms that collusion involving members of An Garda Siochana did exist.
"As to who may have been involved, the family would seek assurance:
"From the Commissioner of An Garda Siochana that a full investigation into these revelations has been initiated with a view to identifying all members of his organisation who may have colluded in these murders, in particular who is the 'fourth Garda Officer, now retired';
"From the Chief Constable of the Police Service of Northern Ireland that these unsolved murders will be re-visited with an examination of all intelligence and evidence available, including that revealed as a result of the Smithwick Tribunal;
"An assurance that both police organisations will provide a full, open and transparent exchange of intelligence and available evidence.
"They should provide further assurances that they will work tirelessly towards bringing to justice any person who had any part in the murder of Chief Superintendent Breen and Superintendent Buchanan, irrespective of what jurisdiction or organisation those persons may belong."
The two murdered officers were the most senior ranking members of the Royal Ulster Constabulary (RUC) killed during the Troubles.
They were caught in an IRA ambush in south Armagh as they returned from a meeting with Garda officers in Dundalk, sparking claims the IRA was tipped off.
The inquiry has focused on former garda officers Owen Corrigan, Leo Colton and Finbarr Hickey, who deny passing information.
A lawyer for one of the three men accused the PSNI of a "shameful injustice" by keeping hold of information that has now pointed the finger at a separate individual.
With the inquiry drawing to a close the Buchanan family said: "It has been mentioned earlier that there was disappointment that this intelligence material was withheld for possibly seven years.
"A close review of the transcript of the evidence and consideration of the change of 'primacy' relating to intelligence following the St Andrews Agreement suggests that while the material was obtained by the PSNI it would undoubtedly have been under the control of the Security Services in London. The Buchanan family would seek clarification on this point."
The family said they had received considerable support over the years from the RUC and PSNI.
They added: "The revelation on Wednesday that the PSNI 'held back' such important information was extremely hurtful."
The relatives thanked all those who gave evidence to the inquiry and appealed for anyone else with information to come forward.
A statement from the family concluded: "They also request that anyone who can assist the police in any further investigation in either jurisdiction to please do so."