Northern Ireland Secretary Peter Hain today promised "full co-operation" with investigations into allegations of collusion involving British security forces in the 1970s.
Mr Hain said the Irish Government was "entitled to feel extremely strongly" about the issue, which is being investigated by the Dail.
"These were appalling atrocities and shameful in every respect, and we pledge our full cooperation in seeking to do what we have to do," he said.
"We are taking this matter forward and we will obviously want to co-operate."
Mr Hain was speaking after the British-Irish Inter-Governmental Conference (BIIGC) in central London, during which the collusion allegations were raised by Minister for Foreign Affairs Dermot Ahern.
Last month an Dail committee found there was widespread collusion between security forces and loyalist paramilitaries in three 1970s atrocities that claimed 18 lives.
They included the Miami Showband massacre and the bombing of Kay's Tavern in Dundalk and the Three Star Inn in Castleblaney, Co Monaghan.
Mr Ahern warmly welcomed the assurances from Mr Hain tonight.
"The fact of the matter is they have been the source of some very serious disagreements between the British and Irish Governments over the years, but with the co-operation of the British Government we believe we can bring some finality to this," he said.
The two ministers also told a joint press conference that the St Andrews Agreement timetable for securing devolution in Northern Ireland would not be changed.
Mr Hain said January would be crucial, and if the parties were not ready to call elections by the end of the month the process could fail.
"If there's no election there will be dissolution (of the Stormont Assembly)," he said.
"People need to be absolutely clear about that." He added:
"If this process falls over at any point there will be dissolution."