France has given verbal warnings to two British boat crews who were fishing in waters off its port of Le Havre, the government says, as tension simmers between the neighbours over post-Brexit arrangements.
The French maritime ministry said it gave the warnings overnight to the two boats, one of which was re-directed to the French harbour.
The captain of the latter boat risked legal action and confiscation of his catch, it added.
France says its fishermen lack half the licences needed to fish in British waters, which Paris says they are owed after Britain left the European Union.
On Wednesday, France issued a list of sanctions that could take effect from November 2 unless there is sufficient progress in the fishing row with Britain, saying it was working on a second round that could affect power supplies to its neighbour.
France could step up border and sanitary checks on goods from Britain, deny its fishing boats access to designated ports, and stiffen checks on trucks travelling between the two countries, the French maritime and European affairs ministries said in a joint statement.