French fishermen have been accused of throwing insults, rocks and smoke bombs at their British rivals in the English Channel in a vicious scrap over scallops.
The clash happened around 12 nautical miles (22km) off the Normandy coast, near the Bay of Seine.
British boats are legally entitled to fish in the scallop-rich area.
But their presence has infuriated the French, who accuse the British of shamelessly depleting shellfish stocks.
Now UK fishermen are demanding government protection, while the French bewail the loss of a “primary resource”.
What exactly happened?
Around 40 French boats gathered overnight on Monday in protest against so-called British “pillaging”.
“The French went to contact the British to stop them working and they clashed with each other,” said Normandy fishing chief Dimitri Rogoff. “Apparently there was stone-throwing, but no injuries.”
Some boats were damaged in the skirmish, with three suffering holes, footage from France 3 Normandie showed.
The British couldn’t match the local armada for numbers. With about five boats to 35 French vessels, they were ultimately chased away.
Two British boats, Golden Promise and Joanna C, returned to Brixham harbour with damaged windows.
The crews alleged they were surrounded and had rocks and metal shackles thrown at their boats.
A video published by French media appears to show a Scottish scallop dredger, the Honeybourne 3, colliding with nearby vessels.
Why has it all blown up now?
Tension has rumbled for 15 years, but in the past five a deal has prevailed – larger British boats stayed out of the area in exchange for more fishing rights.
British boats can gather scallops year-round, but French law restricts the scallop fishing season to between 1 October and 15 May.
This year, the fed-up French rejected that agreement.
“For the Brits, it’s an open bar – they fish when they want, where they want, and as much as they want,” Mr Rogoff complained.
“We don’t want to stop them from fishing, but they could at least wait until 1 October so that we can share.
“Scallops are a flagship product for Normandy, a primary resource and a highly sensitive issue.”
How have the Brits reacted?
Mike Park, chief executive of the Scottish White Fish Producers Association, described the clashing incident as “clear piracy”.
Speaking about the Scottish boat, he told BBC Scotland: “He’s fully entitled to be there. UK vessels can enter that French zone, it’s not illegal.
“The Peterhead vessel is going about its business. The French vessels are probably attacking it.”
Appeals for calm were issued by Britain’s National Federation of Fishermen’s Organisations, which said some boats had been filmed manoeuvring dangerously.
“We have raised the matter with the British government and asked for protection for our vessels, which are fishing legitimately,” its chief executive, Barrie Deas, said.
“The deeper issues behind the clashes should be settled by talking around the table, not on the high seas where people could be hurt.”