The government said it was “disappointed” by threats of protest action from French fishermen amid the escalating dispute over post-Brexit fishing rights.
It comes after representatives of the French fishing industry signaled they could blockade Calais and other ports to halt exports to the UK.
The measures would be a protest against what they say is Britain’s refusal to grant them more licenses to fish in British waters.
A British government spokesperson said: “We are disappointed by the threats of protest activity and we expect the French authorities to ensure that there are no illegal actions and that trade is not affected.
“In total, we have authorized almost 1,700 EU vessels; our approach to licensing has been reasonable and fully consistent with our commitments in the Trade and Cooperation Agreement (ACT).
“We continue to work with the Commission and the French authorities and will consider any further evidence provided to support the remaining license applications.”
Talks are underway between Britain, France and the European Commission to settle the main source of contention, namely the number of fishing licenses in the waters around the British coasts for small French vessels which can prove that they have historically operated there.
But French fishermen are “exasperated” by the “endless months of waiting” and are ready to “exert more pressure” on the United Kingdom, according to the fisheries committee of the northern Hauts-de-France region.
The president of the organization, Olivier Lepretre, said on Monday: “We are going to hamper English interests.
“We also want to repeat to UK Prime Minister Boris Johnson: your fishermen have access to European waters, we don’t see why we cannot access UK waters – as was specified in the Brexit deal.”
He did not say what action would be taken, but said plans would be made by the end of the week.
Cross-Channel tensions over fishing have been going on for a long time, with the first rows leading to the dispatch of Navy ships to Jersey over concerns over a blockade of the island.
On Monday, the French Minister for Europe, Clément Beaune, said all options remained on the table in the area of fisheries.
He said France wanted a “constructive solution” on the number of licenses granted to trawlers to fish in British waters, which he called still “not at all” satisfactory.
But he said Paris would consider taking action if the dispute is not resolved, with threats including tighter controls and a ban on British trawlers from landing their catches in French ports.
Meanwhile, the European Commission has stepped up pressure on the UK in the dispute.
Commission spokesperson Tim McPhie said: “There has been progress with pending license applications, but the process is moving too slowly.”
The Commission will ask for “an intensification of the process within a clear time frame”, he added.