Jersey on Thursday called France's threat to cut power to the British crown dependency over fishing rights "unacceptable" and said it was unlikely to be carried out.
Britain has refused to grant all the fishing licences sought by French boats as part of a post-Brexit access deal, leaving Paris furious and fishermen worried for their livelihoods.
France this week reiterated a threat that it could cut off electricity to the Channel Islands, which are close to the French coast and depend on France for their electricity.
The threat was "disproportionate" and "unacceptable" and violated Britain's post-Brexit treaty with the European Union, Jersey's Minister for External Relations Ian Gorst told reporters via videolink.
Gorst said such a move would deprive 108,000 islanders of power, as well as Jersey's hospital and schools.
"I do not believe therefore it will happen," he said.
But should France carry out the threat after all, "we do have contingencies in place", he said.
French European Affairs Minister Clement Beaune warned on Tuesday that France was ready to step up the pressure on the United Kingdom over the fishing issue, saying it was London that stood in breach of post-Brexit deals.
"For example, you could imagine the Channel Islands, where the United Kingdom depends on us for its energy supply...," Beaune said.
He did not expand further, but the warning echoed an earlier threat by Fisheries Minister Annick Girardin who said in May that the fishing row could have an impact on "the power supply by undersea cable" from France to Jersey.
Fishing rights for EU boats in UK waters were a key stumbling block to negotiations for a post-Brexit trade accord between London and Brussels after Britain's exit from the bloc on January 1, 2021.
The dispute flared in May when a flotilla of around 50 French trawlers massed in front of the Saint Helier harbour on Jersey, a self-governing territory that along with fellow crown dependency Guernsey depends on Britain for its defence.
The protest sparked a tense standoff that even drew in French and British military vessels.
Since then, French fishermen have applied for the new access licences but complain of onerous paperwork and a requirement to prove they had fished in British and Jersey waters before Brexit, not always an easy task, especially for smaller boats.
Last week, Britain said it would grant just 12 out of 47 applications for new licences for small EU boats, while Jersey issued 64 full and 31 temporary licences but refused 75 applications.
"We've done everything we can to enable licenses to be issued to those vessels who can prove they've fished in our waters and we continue to do so," Gorst said.