Paris even went as far as suggesting it could restrict energy supplies to the Channel Islands if no deal is reached with the UK as relations since the EU departure further soured.
No 10 said the threats do not seem to be compatible with “international law” and vowed an “appropriate and calibrated response” if Paris does not back down.
France has been angered by a decision from the UK and Jersey last month to reject dozens of licences for French boats to fish in their waters, arguing it breaches the Brexit deal.
If an agreement over the licenses is not struck by Tuesday, France said it will block British boats from some ports and tighten checks on vessels travelling between France and the UK.
A joint statement from the French ministers for Europe and for maritime affairs added that they do not exclude measures targeting energy supplies to Britain in the coming weeks.
Brexit minister Lord Frost said: “It is very disappointing that France has felt it necessary to make threats late this evening against the UK fishing industry and seemingly traders more broadly.
“As we have had no formal communication from the French Government on this matter we will be seeking urgent clarification of their plans. We will consider what further action is necessary in that light.”
A UK Government spokeswoman added: “France’s threats are disappointing and disproportionate, and not what we would expect from a close ally and partner.
“The measures being threatened do not appear to be compatible with the Trade and Cooperation Agreement and wider international law, and, if carried through, will be met with an appropriate and calibrated response.”
1/2 It is very disappointing that France has felt it necessary to make threats late this evening against the UK fishing industry and seemingly traders more broadly.
We set out our position earlier this evening. https://t.co/2kuHofrWsw pic.twitter.com/kfhH2ML6hz
— David Frost (@DavidGHFrost) October 27, 2021
She said that Britain will express its concerns both to the EU and the French Government, and argued that the UK has granted 98% of licence applications from European vessels.
But the dispute continues over 31 vessels which the UK did not approve licences for, arguing that they did not have supporting evidence for their applications.