A vessel sailing under the Maltese flag has been anchored off Port-la-Nouvelle (Aude) since Saturday 8 May.
Alerted by the captain, a team from Smur from the Narbonne hospital center and firefighters from Sdis de l'Aude noted the presence of a cluster.
Twelve of the eighteen sailors were positive for Covid-19.
Four of them were the subject of a medical evacuation, two of which were placed in intensive care.
The other fourteen crew members are placed in strict isolation on board the ship.
Due to the weather conditions this weekend, the ship was taken to safety inside the port.
The nationality of the crew members was not specified by the prefecture.
The tanker came from the Netherlands
The tanker had left the Netherlands before crossing the Strait of Gibraltar to sail in the Mediterranean.
The crew must be relieved by the owner of the vessel.
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