France seized a British trawler fishing in its territorial waters without a license on Thursday (October 28).
It also issued a warning to a second vessel as a dispute over access to fishing grounds after Brexit escalated.
France is furious that Britain has refused to grant its fishermen the full number of licenses to operate inside British waters that France says is warranted.
Clement Beaune is France's Europe minister:
"It's time for us to get respect. I stand by the fact we issued threats and pursued dialog until now, since it allowed our fishermen to have a bit over half of the fishing licenses today. We have to also see the glass half full but that's not enough and not acceptable at all. So now, we need to speak the language of strength since that seems to be the only thing this British government understands."
The French government said it would from November 2nd impose extra customs checks on British goods entering France.
That raises the prospect of more economic pain before Christmas for Britain, which is facing labor shortages and rising energy prices.
It is also reviewing a second round of sanctions and does not exclude a review of its exports of electricity to Britain.
France's Seas Minister on Thursday told French radio, "It's not war, but it is a fight."
British Prime Minister Boris Johnson's office did not immediately respond to a request for comment on the detained trawler.
Britain has said France's planned acts of retaliation will be met with an appropriate and calibrated response.