French authorities were trying to contain an oil spill off the Atlantic coast on Thursday after an Italian cargo ship, carrying 45 containers of "dangerous materials", sank in the Bay of Biscay.
The sheet of oil is reportedly 10-kilometres long and one-km wide and is threatening to hit parts of the country's southwest region near Bordeaux over the weekend.
"According to our forecasts, fragments could reach some areas of the coast in Nouvelle-Aquitaine by Sunday or Monday owing to bad weather, which also risks making the anti-pollution operation more difficult," environment minister Francois de Rugy said on Wednesday.
He also said four ships would be deployed to try and contain the oil slick and will prepare for a clean-up operation on land.
The Grande America vessel was en route from Hamburg to Casablanca when a fire broke out late on Sunday. The 27 people onboard were evacuated before the ship sank some 300km west of the city of La Rochelle in southwestern France.
"For now the possible pollution risk consists mainly of the 2,200 tonnes of heavy fuel oil on board," Jean-Louis Lozier, head of the regional maritime authority, told reporters in Brest.
Lozier added the Italian ship's owner had indicated that 45 of the 365 shipping containers onboard carried "dangerous materials", which include 100 tonnes of hydrochloric acid and 70 tonnes of sulphuric acid, as well as 2,000 vehicles.
Lozier said the pollution risk "would be very localised", as much of the chemicals were already burned in the fire.
However, the French environmental group Robin des Bois (Robin Hood) said it intends to file a complaint over environmental damages.