The French government said they're looking into retaliatory measures after the UK and Jersey awarded just a small number of licences to French vessels.
French Prime Minister Jean Castex has called on the EU to get tougher with the UK over post-Brexit fishing rights.
Speaking in Parliament, Castex said he had "seized" the presidency of the European Commission over the ongoing fishing dispute between France and the UK, calling for Brussels to "do more" and be "tougher" with London.
"If this is not enough, then we will refer the matter to the arbitration panel of the agreement to lead the British to respect their word (and) we will question all the conditions for the more global implementation of the agreements concluded under the aegis of the European Union, but also if necessary the bilateral cooperation that we have with the United Kingdom," he said.
The post-Brexit agreement, reached at the eleventh hour on Christmas Eve, provides for European fishermen to continue to work in some British waters on condition that they obtain a licence that requires them to prove that they used to fish there before Brexit.
The Channel Island of Jersey announced last week at it had granted 64 definitive licences to French vessels and 31 temporary ones — compared to 169 requested by Paris — and rejected 75 applications. The day before, London granted 12 additional authorisations in its waters, within the limit of 6 to 12 nautical miles of its coasts — less than a quarter of the 87 requested by France.
Castex's comments came hours after France's Europe Minister, Clément Beaune, warned that Paris and Brussels would take "measures to put pressure on the United Kingdom" within days.
"For example, we can imagine the Channel Islands, the United Kingdom depending on our energy supply..." he told Europe 1 radio, without finishing his sentence, suggesting France could cut Jersey's power supply.
This particular threat was already issued in May by Annick Girardin, France's Minister for the Sea. She said last week that France was readying "retaliatory measures" for the low number of licences granted to French vessels.
Beaune warned that "our patience has a clear limit, that of exasperation and that of our fishermen."
"We have been talking calmly and kindly for nine months. That's enough," he added.
French and EU lawmakers are scheduled to meet on Wednesday with the regional councils of Brittany, Hauts-de-France and Normandy, as well as the departmental councils and mayors concerned.
European fisheries ministers will meanwhile convene in Luxembourg next week.