One of these is in Brittany and the prime minister went to visit the place himself.
Local residents in the area of Saint-Michel-en-Greve have long criticised the government for not doing anything about the matter after the weed has been growing there for several years.
The green marine algae are also causing a problem along the British coastline, mainly in Dorset, Hampshire, the Isle of Wight and West Sussex.
The seaweed becomes a danger as it rots because it releases hydrogen sulphide gas that is poisonous.
