The government has hit out at British Prime Minister David Cameron over his refusal to order a public inquiry into the controversial murder of Belfast solicitor Pat Finucane.
Tanaiste and Foreign Affairs Minister Eamon Gilmore accused London of falling short of a deal struck at the Weston Park peace talks in 2001.
Signalling a souring in relations between both governments, Mr Gilmore said Dublin had already conveyed its dissatisfaction and disappointment and would be preparing a formal response in the coming days.
"There are sometimes occasions when frank disagreements arise between states," he said.
"This is one on this occasion."
The Finucane family walked out on a meeting with Mr Cameron at Downing Street last Tuesday when he told them he would ask a senior barrister, Desmond de Silva QC, to review the files into the killing rather than set up a full inquiry.
Mr Gilmore said Taoiseach Enda Kenny was only told about the decision during a telephone call from Mr Cameron shortly before the meeting.
Both Mr Kenny and Mr Gilmore have expressed their dissatisfaction personally with Mr Cameron and Northern Ireland Secretary of State Owen Paterson.
The Finucane family's legal team will work with government officials in the coming days on their contacts with the British government in recent months ahead of a formal response from Dublin. Top level meetings are expected to follow.
Mr Gilmore said Ireland had an agreement with Britain over the investigation of certain murders involving alleged State collusion during the Troubles with which Mr Cameron's government had to comply.