PARIS (AFP) - French customs agents have seized 2.25 tonnes of cocaine, their largest haul ever, from a sailboat in the Caribbean, the government said Saturday.

Authorities made the seizure Wednesday about 200km off the French island Martinique when they intercepted a boat "falsely flying an American flag".

Three people were arrested aboard the vessel, said the statement from France's finance ministry.

The cocaine haul amounts to about a third of the 6.6 tonnes of the drug seized over the whole of last year by French customs officers.