The seizure by two navy ships on Monday followed a tip-off by anti-drug and maritime intelligence authorities and British police, authorities in France's northwestern Atlantic Maritime region said.

The operation was part of France's Corymbe naval mission, which has been deployed in the Gulf of Guinea since 1990 to ensure security in an area where piracy is fairly common.

"In total, 9.6 tonnes of cocaine with a market value of nearly 519 million euros ($609 million) was seized from a boat," the Atlantic Maritime prefecture said, adding that the vessel was not registered in any country.

By the end of August, the French navy had already seized nearly six tonnes of cocaine off the coast of west Africa.

With more than 45 tonnes of drugs intercepted by the French navy, seizures made in 2025 have already reached a record, Admiral Nicolas Vaujour, Chief of Naval Staff, said at the time.