PARIS — The French military says it seized 6 tons of cocaine with an estimated value of up to 1 billion euros ($1.2 billion) from a cargo ship traveling off the west coast of Africa.

It was France’s largest-ever drug seizure at sea, and involved coordination with international partners, according to a statement Tuesday from the French military.

The statement said the cargo ship had traveled from South America.

Alerted to suspicious cargo, members of a French patrol in the Gulf of Guinea confronted the ship Sunday morning from their helicopter carrier. Military reinforcements were brought in to help remove all the cocaine, the statement said.

The helicopter carrier is part of France’s Corymbe mission aimed at helping countries in the region with security on what is a frequent trafficking route.