The French government has threatened to use energy supplies as a way to "put pressure" on Britain to comply the Brexit agreement.
Speaking on Tuesday morning the country's Europe minister Clement Beaune told Europe 1 radio that France was exasperated by restrictions on French fishing fleets.
"Enough already, we have an agreement negotiated by France, by Michel Barnier, and it should be applied 100 percent. It isn't being," Mr Beaune said.
"In the next few days, and I talked to my European counterparts on this subject yesterday, we will take measures at the European level or nationally, to apply pressure on the United Kingdom."
He said: "We defend our interests. We do it nicely, and diplomatically, but when that doesn't work, we take measures."
The minister did not elaborate on exactly what action could be taken, but added: "For example, we can imagine, since we're talking about energy, ... the United Kingdom depends on our energy supplies. It thinks that it can live all alone, and bash Europe."
According to the latest UK government statistics France exported a net 8,700 gigawatt hours of energy to Britain in 2020.
The warning by France comes as Britain is set to enter what ministers have called a “difficult winter” – with soaring energy prices and shortages of some products including fuel.
But any action on energy may come with practical issues for France, given Britain is also effectively a transit point for electricity exported to other countries like Ireland.
The warning from the French minister was triggered by a row over access for French fishing fleets to territorial waters around Jersey, a British Crown dependency.
A large chunk, around a third, of French boats applying for licences to fish around Jersey have been turned down.
Jersey says the 75 rejected French boats were not granted licences as “they do not meet the criteria and have either not fished in Jersey waters during the relevant period or have not been able to evidence their activity”.
The island government says the vessels are being “given 30 days’ notice of the end of the transitional arrangements, after which they will no longer be able to access Jersey waters”.
This row over fishing around Jersey comes as Britain demands renegotiation of other parts of the agreement, relating to Northern Ireland.
Brexit minister Lord Frost on Monday reiterated that the government was prepared to trigger Article 16 of the Northern Ireland protocol, effectively suspending the agreement. The EU says the deal must be implemented as agreed by the UK says the EU should be more flexible.
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