Crew members from the Jura boarded the Northern Celt as it prepared to cast nets near Rockall.

"We were fishing in Rockall and members of the crew from the Jura boarded us," fisherman Adrian McClenaghan told RTÉ News.

"They informed us that we could no longer fish inside the 12-mile limit of Rockall."

Mr McClenaghan has since been handed a temporary license to fish in UK waters, but claims that he cannot afford not to fish there, as it accounts for 30% of his annual catch.

Rockall is a tiny uninhabited island, no more than 25 metres wide, around 400km from the coast of Co. Donegal, and around 370km from the coast of Scotland.