British scallop trawler F/V Cornelis, owned by Scotland-based Macduff Shellfish, has been detained by French authorities amid warnings that unless a post-Brexit battle over fishing rights is resolved, UK boats will be prevented from landing their catches in French ports beginning next week.

The fight began almost as soon as the United Kingdom left the EU's orbit at the end of last year.

French fishermen have been angered by the number of licenses issued allowing them to fish in UK waters.

While the UK government has insisted French vessels must prove they were fishing consistently in British waters before Jan. 1, French fisherman say the evidence requirements are too onerous, placing the UK in breach of its post-Brexit treaty obligations.

Almost 1,700 EU vessels have now been licensed to fish in UK waters, according to the UK government, more than 700 of which are French, a number disputed by the French government.

While much of the dispute now centers on a six- to 12-mile zone off the British coast, French authorities are furious that more than 50 boats applying to fish in the waters off Jersey, a British crown dependency, have been rejected by that island’s government.

Andrew Brown, director of Macduff Shellfish which owns the detained vessel, told Sky News it appears the vessel is being used as a "pawn in an ongoing dispute" between France and the United Kingdom.

Macduff also released a statement defending its activities as "entirely legal."

"We are looking to the UK government to defend the rights of the UK fishing fleet and ensure that the fishing rights provided under the Brexit Fishing agreement are fully respected by the EU," the company said.

"We will vigorously defend ourselves against any claims."

So far, without the backing of other EU nations, France also has threatened to step up checks on cross-Channel trade.

There also rumblings that the UK’s energy supply could become a potential target. French nuclear power stations supply the UK and Jersey using undersea cables.

Macduff is a division of Canada's Clearwater Seafoods, which itself was acquired earlier this year by Premium Brands and a coalition of Canadian First Nations.

Besides the impounding of Macduff's Cornelis trawler, another UK vessel also reportedly received a verbal warning as it fished in waters off the French coast.

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