The U.K. government hit back at France over its proposed retaliatory measures in a dispute over fishing access, as post-Brexit tensions between the two countries rose further.

“France’s threats are disappointing and disproportionate,” Prime Minister Boris Johnson’s office said in a statement Wednesday, after a French government spokesman said they may disrupt the flow of trade with Britain and energy supplies to the Channel Islands due to a lack of fishing licenses given to French boats since Brexit.

“The measures being threatened do not appear to be compatible with the trade and cooperation agreement and wider international law,” Downing Street said, referring to the post-Brexit trade deal signed on Christmas Eve last year. The measures “will be met with an appropriate and calibrated response.”

Adding to the tension, French authorities on Wednesday seized an English vessel that was fishing off Le Havre without a license, according to a tweet by Maritime Affairs Minister Annick Girardin.

Access to British waters for EU boats has been a long-running sore point in the post-Brexit relationship between the U.K. and its largest trading partner, leading to a major escalation earlier this year when both Britain and France deployed naval warships in the English Channel. France’s complaint is that some of its boats are unfairly being denied access to fishing grounds where they have operated historically, whereas Britain says it is merely enforcing the terms of their post-Brexit accord.

France has set the U.K. a deadline of Nov. 2 to give boats more licenses, after which it says it will implement its retaliatory measures. These include systematically applying customs and health checks to goods unloaded in French ports, which likely cause major traffic queues around the critical Port of Dover.

Both Johnson and French President Emmanuel Macron will be in Rome this weekend for the G-20 summit where they may meet Sunday, two days before the deadline.

“Our patience is reaching its limits,” French government spokesman Gabriel Attal said to reporters in Paris on Wednesday. “Our wish is quite simply that the accord that we reached can be respected.”

Also on Wednesday, a French patrol boat found an English fishing vessel operating without a license, according to a statement tweeted by Girardin, the maritime minister. The boat was ordered into port at Le Havre. Its catch can be seized and the boat held until a guarantee is paid, according to the statement. The operation was part of tougher enforcement undertaken by the French because of the dispute over fishing licenses, according to the ministry.

A problem in the fishing dispute is that the U.K. is asking for boats to provide evidence that they have fished in British waters historically, something that older French vessels with less sophisticated technology have struggled to do. Another issue is fishermen who’ve operated in waters historically, but have recently acquired new boats which won’t have fished in those areas.

The U.K. government says it has granted 98% of license applications from EU vessels since Brexit, while France says the U.K. is introducing evidence requirements for applications that weren’t present in the Brexit trade deal.

Marex Media