Minister for Foreign Affairs Simon Coveney has warned it would be a "big political mistake" for the British government to trigger Article 16 of the Brexit deal's Northern Ireland protocol.
He said the European Union response would be robust and that he thought the bloc would also maintain solidarity with Ireland and a hard border on the island would be avoided.
Mr Coveney made his remarks in an interview with former RTÉ journalist Seán O'Rourke on the last day of the MacGill Summer School forum.
He was asked about a Sky News report that the British ministers are holding discussions about the repercussions of triggering Article 16, which would suspend full co-operation with the Northern Ireland protocol.
Mr Coveney said it's certainly a possibility that the British government will do this, pointing to the stance taken by UK prime minister Boris Johnson and chief negotiator David Frost.
“It would be a big political mistake. . . because I think the EU will respond very robustly.”
Mr Coveney said the EU has shown flexibility on the protocol and if the UK government acted unilaterally on that, the EU view would be they are “not an honest partner in trying to find common ground”.
He said he doesn’t think the triggering of Article 16 would result in a hard border being imposed to protect the EU single market, pointing to the “incredibly strong” solidarity with Ireland in the EU.
“I don’t believe the EU. . . will allow a British government to act unilaterally to break international law and to make Ireland the victim of all of that by calling into question our place in the EU and its single market.”
He said there would be “consequences” for the UK if Article 16 is triggered but declined to outline what they would be “because someone will accuse me of raising threats”.
Mr Coveney said there is “active and robust discussion” taking place between the EU and the UK and said he thinks “ we need to give the time and space to the negotiating teams”.
Separately, the Fine Gael Minister was asked if he has a response to people who believe the next government south of the Border will inevitably include Sinn Féin.
Mr Coveney said he didn’t agree.
“They have a very significant mandate and we need to respect that. That’s democracy.”
But he also claimed: “They introduce a very aggressive and in some cases divisive style into politics.”
He said Fine Gael "intends to govern well" and work with Fianna Fáil and the Green Party to "show that the centre of Irish politics is strong and can deliver".Asked if he could sit in government with Sinn Féin, Mr Coveney replied: "I don't think so."
He added: “Look, who knows what the future will hold in terms of changes and approaches and so on.
“But, I don’t believe that my party and Sinn Féin are compatible partners for a stable government.”