Fisherman licences, post-Brexit
The UK insists it reserves the right to respond - after a British trawler was detained in France over a row about post-Brexit fishing rights.
Paris has warned it could ban UK boats from French ports from next week if the issue's not resolved.
The French ambassador has been summoned to a meeting in London, to explain why France is threatening sanctions.
The country's agriculture minister says they're justified to do so, as there has been no progress over post-Brexit fishing licences.
British environment minister, George Eustice, says introducing sanctions would be completely out of order:
