Fears Brexit could spark a fresh row over Rockall
Brexit could reignite an age-old controversy over ownership of an isolated Atlantic islet off the Donegal coast.
Rockall is under 300 miles from Scotland and Ireland's western extremities.
The pudding-shaped remnant of an extinct volcano was the subject of diplomatic tussles over the surrounding fisheries and oil-rich sea bed.
Its sovereignty was finally settled in Scotland's favour in 2014 after being sparred over for decades.
Some in the Republic fear the UK's exit from the EU could cause Britain to "pull up the drawbridge" on international use of the area.
Jane Morrice, a former European Commission representative in Northern Ireland, warned: "The fact that the rocky outcrop in the North Atlantic is claimed by the UK as part of Scotland could make it a small but serious point in future negotiations."
She said talks over fishing rights would involve a complicated agreement with the potential to make or break the Northern Irish fishing industry.
Eamon O'Cuiv, Fianna Fail's island affairs spokesman from Galway in Ireland's west, said: "In the event of a hard Brexit, there is a strong desire by many in the UK fishing industry to 'pull up the drawbridge' and push for a ban on non-UK fishing fleets fishing in UK waters so that the currently shared fishing zone will be the UK's and the UK's alone."
Sean O'Donoghue, CEO of the Killybegs Fishermen's Organisation in Co Donegal, added: "We can fish at the minute in Rockall as we have fishing rights there but when the UK leaves they will no longer be part of the Common Fisheries Policy and there will have to be some detailed discussions around the fisheries, which are very difficult to resolve."