The UK has been warned "next time it will be war" as tensions rise with France over a fishing dispute.
Britain withdrew its Royal Navy vessels from the waters off Jersey on Thursday but said it would remain on standby to support the Channel island after a dispute with France over post-Brexit fishing rights escalated rapidly.
France and Britain both deployed maritime patrol vessels to the area after a flotilla of French trawlers sailed in protest to Jersey's main harbour and a French minister suggested earlier in the week that Paris might cut electricity to the island.
French fishermen say they are being unfairly deprived of access to rich fishing grounds off the coast of Jersey, a self-governing British Crown Dependency.
Jersey says it is following the rules for issuing licenses set out in Britain's post-Brexit trade deal with the European Union. Britain said it backed Jersey. The EU called for calm.
French fishing boats leave Jersey after protest
After the French fishing boats left the area, Britain said its Royal Navy Offshore Patrol Vessels would prepare to return to port in the UK as the "situation is resolved for now".
"We are pleased that French fishing boats have now left the vicinity of Jersey," a government spokeswoman said.
"We remain on standby to provide any further assistance Jersey requests."
British Prime Minister Boris Johnson, who led the 2016 Brexit campaign, had cast the trade deal as a way to take back control of the United Kingdom's destiny after Brexit.
On Thursday, he had said the two vessels would remain off Jersey as a precautionary measure, according to his office.
An official from the French presidency said the deployment from both France and Britain was aimed at preventing clashes between trawlers on opposing sides of the row.
French fishermen however are refusing to back down, with a crewman telling the Telegraph: "We will go back, and next time it will be war.”
France concerned over Jersey stance
France is angry that on April 30 Jersey issued 41 licences with what the Paris government called unilaterally imposed conditions, including the time French fishing vessels could spend in Jersey's waters.
Hugo Lehuby, spokesman for the Normandy Regional Fisheries Committee, said talks between island officials and representatives of the fishermen were not positive.
"We're getting deeper into deadlock," Mr Lehuby told Reuters.
"Either this gets resolved, or retaliatory measures are taken."
Jersey officials have said the accord stipulates licences take into account how much time a vessel spent in Jersey's waters before Brexit.
Britain's Brexit negotiator David Frost said under the terms of the trade deal, Jersey can regulate fishing in its waters.
The European Commission said however that until further justifications had been provided by Britain, Jersey officials should not be attaching new conditions to licences.
"Full compliance with the TCA [Brexit trade deal] is essential in this process," Commission spokeswoman Vivian Loonela told a news briefing.
The fleet of about 50 fishing boats left the shores of Jersey, which lies 22 kilometres off northern France and 137km from Britain's southern coast, in the early afternoon. They had arrived at dawn, with some crew holding red flares aloft.
At least one French trawler entered the harbour and briefly blocked the Commodore Goodwill, a cargo vessel and ferry that connects the Channel Islands to the British mainland.
The French presidency official said the deployment of patrol vessels spoke of France's concern and frustration.
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