LONDON — It has been called the “scallop war” — a simmering rivalry that spilled out into the open again this week when French and British vessels clashed in the English Channel, French fishermen tossed what appeared to be smoke bombs at their rivals, and the British called on the Royal Navy for protection.

Video footage on French state television and on social media showed about 35 small French fishing boats menacing five larger British vessels early Tuesday in a stretch of international waters that separates Britain from the rest of Europe, just off the northwest coast of France.

At least one French boat slammed into the side of a Scottish vessel. The fishermen shouted insults and hurtled smoke bombs through the air.

A French official said no one had been injured in the clash, but called the encounter “extremely dangerous.”

The French argue that British fishing vessels have an unfair advantage. The French government does not allow fishing for scallops to begin until October to preserve the stock.

But the British have no such restrictions. Large boats from as far as Scotland visit these waters every year in hopes of making a good catch, within fishing quotas.

Dimitry Rogoff, head of the regional fisheries committee in Normandy, France, told the Guardian newspaper, “For the Brits, it’s an open bar — they fish when they want, where they want and as much as they want.”

“We don’t want to stop them from fishing,” he added, “but they could at least wait until Oct. 1 so that we can share.” He was not available for comment Wednesday.

The French vessels set out from the Normandy ports of Port-en-Bessin, Courseulles, Ouistreham, Trouville, Honfleur and Le Havre to chase British boats away from the Baie de la Seine, where the seabed is rich in scallops.

One video showed two smaller French boats navigating close to a larger Scottish vessel, with one slamming into its side. (A Scottish ship and its owner were convicted in November of catching scallops smaller than the permitted minimum size and ordered to pay a total of 29,000 pounds, around $37,300.)

Video posted by the master of the French boat showed smoke or steam rising from the larger vessel. The French state television network France 3 said it appeared smoke bombs had been thrown.

“There were some fairly strong clashes,” said Lt. Ingrid Parrot, the spokeswoman for the French regional maritime authority.

“This kind of event is extremely dangerous at sea,” she said, adding that authorities would remain vigilant for signs of flare-ups.

Britain’s National Federation of Fishermen’s Organizations said it had asked the Royal Navy for protection since the vessels were operating in the waters legally.

A statement from the Marine Management Organization, which manages fishing in Britain, was not immediately available.

The tensions between fishing vessels in the Baie de la Seine has existed for more than a decade. The French and British sides previously struck agreements about the scallops in previous years to avoid the very clashes that occurred at dawn Tuesday.

The last time such a clash occurred, in 2012, the French Navy was called to intervene after 40 French boats surrounded five British vessels in the same area.

European Union regulations have for decades given fishing vessels from other member states access to Britain’s fishing stock.

Rogoff said that things might change next year if Britain exited the European Union without a deal.

“After March 29, 2019, they would be treated as a third party and would no longer have access to these areas,” he said of the British vessels.

Fishing waters rights was an issue in the debate before the country voted to leave the European Union, a process known as Brexit. British organizations like Fishing for Leave campaigned to take back control of British waters. On Wednesday, that group condemned the clashes.

In the “soft Brexit” scenario currently being pursued by the government of Prime Minister Theresa May, Britain would not withdraw immediately from the European Common Fisheries Policy.

Fishing accounts for less than half a percent of Britain’s gross domestic product, but English fishing boats currently depend on fishing in E.U. waters and on exporting to the Continent.