As a cargo ship sinks off the coast of France, worries of an oil spill loom.

(Reuters) French authorities battled on Thursday to contain an oil slick after the Italian Grande America ship capsized in the Atlantic this week.

The Grimaldi Lines container ship capsized and sank on Tuesday, after catching fire while sailing from Hamburg to Casablanca. Britain’s Royal Navy frigate Argyll rescued all 27 crew members from the water.

The ship was carrying 2,200 tonnes of heavy fuel when it sank some 330 km (200 miles) off the coast from La Rochelle in western France. Footage from the French navy showed thick black smoke pouring from the vessel.

French authorities said a slick measuring 10 km (6 miles) long and 1 km wide could reach the coast of southern Brittany by the end of the weekend.

French Prime Minister Edouard Philippe and Environment Minister Francois de Rugy both said they were closely monitoring the situation.

A Grimaldi representative in France declined to comment. Company officials in Italy could not immediately be reached for comment.