Eleven countries, including Belgium, have signed a joint statement criticising the UK for only granting a limited amount of licences to European fishing boats looking to use their waters.
Tensions have been building around the issue since Brexit, and France recently called for a more European front after conversations with Britain broke down into threats, according to Belga News Agency.
“The UK's response to the applications for fishing permits is incomplete and inappropriate,” the French Ministry of the Sea said in a press release, following a European Agriculture and Fisheries Council meeting in Luxembourg.
Belgium, Cyprus, France, Germany, Greece, Ireland, Italy, the Netherlands, Portugal, Spain and Sweden all signed the statement.
The post-Brexit agreement reached late last year between the United Kingdom and the European Union stipulates that European fishermen can continue to fish in some British waters.
However, they have to have a licence that allows them to prove that they have fished there before and the French and British are arguing about exactly what proof is needed.
The United Kingdom and the Channel Island of Jersey granted a total of just over 200 final licences in the fishing areas concerned (the 6-12 nautical mile zone off the British coast and the Channel Islands). France is demanding 244 more.
Belgian fishing boats were granted 17 licences at the start of this year and at the time were pleased with that, as they'd only requested 18.
The French believe that the British are not honouring their commitments and have already threatened to cut off energy supplies to the Channel Islands. Earlier, French fishermen blockaded the main port on Jersey.
“This joint declaration is an important step, because only with a collective response will the European Union be able to face the negotiations with our British partner in a serene way,” Annick Girardin, France's Minister of the Sea, said in the press release.
Girardin also said the European and French responses to the British proposals will be made public later this month.
Agreements on the fisheries sector were at the heart of negotiations on a post-Brexit deal last year.
The re-establishment of control over their own territorial waters was an absolute must for the British, while France, Belgium and some other European member states were - and still are - particularly concerned about the future of their fishing industry.