LONDON (AP) — Britain’s environment minister pledged Friday to retaliate if France carries through on threats to block U.K. ships from French ports, warning that “two can play at that game’’ in the worsening dispute rooted in Britain’s departure from the European Union.

Britain summoned the French ambassador for a dressing-down after French authorities fined two British fishing vessels and kept one in port overnight Thursday.

Since the U.K. left the economic orbit of the EU in January, relations between London and Paris have become increasingly frayed as the nations on either side of the English Channel sort out a post-Brexit path.

France has threatened to block British boats and tighten checks on U.K. vessels unless French vessels get more permits to fish in U.K. waters. France also suggested it might restrict energy supplies to the Channel Islands, British Crown dependencies that lie off the coast of France.

“We will see what they do,” Environment Secretary George Eustice told Sky News. “But if they do bring these into place, well, two can play at that game and we reserve the ability to respond in a proportionate way.”

The U.K. government said France’s ambassador, Catherine Colonna, would be summoned to the Foreign Office on Friday, in an official sign of displeasure.

“We regret the confrontational language that has been consistently used by the French government on this issue, which makes this situation no easier to resolve,” the British government said in a statement.

France vehemently protested the decision last month by the U.K. and the Channel Island of Jersey to refuse dozens of French fishing boats licenses to operate in their territorial waters. Dozens of other licenses were granted. France says the restrictions are contrary to the post-Brexit agreement that Britain signed when it left the EU.

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