DUBLIN: A Scottish patrol vessel stopped an Irish boat fishing from waters in the North Atlantic Ocean, citing Brexit as the reason, Irish media reported.

State broadcaster RTE said on Tuesday evening that Irish trawler The Northern Celt was intercepted and boarded by a Marine Scotland patrol boat on Monday.

The boat had been preparing to cast its nets off the waters of Rockall -- a granite outcrop around 400 kilometres (250 miles) northwest of Scotland and Ireland.

RTE reported the skipper of The Northern Celt was "instructed that he can no longer fish within 12 nautical miles of the disputed rocky outcrop as a result of Brexit".

Britain left the European Union in January 2020 but the bloc's rules continued to apply until December 31, while London and Brussels worked out their future relationship.

A last-minute trade deal, signed on Christmas Eve, includes terms regulating EU access to British fishing grounds.

EU boats will gradually relinquish 25 percent of their current quotas over the next five-and-a-half years, then access will be decided in annual negotiations.

If Britain limits EU access or catches, Brussels can retaliate with tariffs on British fishing products or other goods -- or even suspend much of the trade agreement.

According to RTE, the Scottish patrol vessel "Jura" moved into position around Rockall on January 1 -- the first day after Britain left Europe's single market and customs union.

Rockall was claimed as British territory in 1955 but Ireland has never recognised its sovereignty. Britain's claim to ownership allows it to exercise control of the surrounding waters.

Although the 20-metre wide and 30-metre long rock is unhabitable, its environs are rich with fish stocks and is a strong prospect for oil and gas reserves.

Ireland's foreign ministry told RTE: "We aware of contact between an Irish fishing vessel and a Marine Scotland patrol vessel yesterday, 4 January.

"We are in contact with the Scottish and UK authorities on this."