Minister for Foreign Affairs Simon Coveney has said the first he heard about the British government’s decision to pull out of the London Fisheries Conventions was through the media.
The move will mean that trawlers from the Republic of Ireland will no longer be allowed to fish within 12 nautical miles of the UK coastline.
Speaking as he and his Finnish counterpart toured the border region, Mr Coveney said that as a former minister for agriculture and the marine, he knows how difficult it will be.
He said part of the broader talks on Brexit will need to take place around fishing.
Mr Coveney and Timo Soini met in Monaghan this morning, where they discussed Brexit-related matters.
Finland will hold the EU presidency in the second half of 2019, when Brexit is actually happening.
Mr Soini said it was important that "like-minded countries" work together in the EU after the UK leaves.
Mr Coveney said the trip to the border was to reinforce the point that there is an invisible border and "we want to maintain that through the Brexit process".
He also called on parties involved in the power-sharing talks in Northern Ireland to redouble their efforts to get the Assembly up and running again.