Wind gusts of up to 130 kph pounded France's western coast in the early hours of Friday, causing a cargo ship headed for Malta, the 109-metre TK Bremen, to run aground off Brittany. The crew were rescued by helicopter.
French television showed footage of black fuel washing up on a sandy beach in Brittany, although the damage is expected to be limited because the leak was coming from one compartment in the ship's supply of fuel, police said.
Maritime authorities were planning to deploy equipment to contain a 1-km slick and empty the stricken ship's tanks of around more than 200 tonnes of fuel.
Early on Friday the storm's heart hung over the northernmost Pas-de-Calais region of France and was headed eastward in the direction of Belgium, according to the latest update from France's national weather service.