Foreign Affairs Minister Simon Coveney has said the Brexit negotiations with the UK are set to focus on securing a 'core agreement on trade'.
He also said that it is now "quite clear" that there will not be an agreement in several areas when Britain officially leaves the bloc at the end of this year.
His comments come a week after the European Commission started legal action against the UK over its plan to breach the Brexit Withdrawal Agreement.
European Commission President Ursula von der Leyen said Westminster’s Internal Markets Bill was "in full contradiction" to the Northern Ireland Protocol, which prevents the return of a hard border in Ireland.
The controversial legislation overrides the protocol by overwriting the requirement for businesses to file customs paperwork when trading from the North into Britain and removing the UKs obligation to notify Brussels of any state-aid decisions affecting the North.
Britain will leave at the end of the December, which marks the end of its tranisition period out of the single market.
Mr Coveney told the Oireachtas Committee on European Union Affairs the 'best case scenario' now is to get a very basic trade deal by the end of the transition period.
But he said that even that would be a significant achievement.
"There are 11 different areas in the Future relationship negotiation that are all moving forward in parallel with each other.
"It's quite clear that in many of those areas, we're not going to get a permanent and comprehensive agreement on a future relationship.
"And so the focus I think at this stage is on getting a core agreement on trade and what is required to do that".
"In my view what will happen here is if there's not a trade deal, and if the UK decide to breach international law and not implement what they're required to implement under the protocol, then that creates a new relationship - and I think quite a negative one - between the EU and the UK.
"But I think the solidarity for Ireland in that circumstance, where again we kind of get squeezed in the context of the breakdown of agreements - I think there would be extraordinary solidarity for Ireland in that situation.
"And I think we'll get a lot of support and help from an EU perspective - and all the focus will be on the British government following through on what they have a legal obligation to follow through on, and legal action if necessary to do that.
"But if that situation unfolds, it will be a monumental failure of politics and diplomacy and self-harm - for Britain in particular, bur also with the implications impacting on Ireland in a very negative way as well as many other countries in the EU.
"And I don't think it'll come to that, and I think the British government would see the folly of that approach."