The carcasses of another 18 wild boar have been washed up on a beach in Northern France.
It brings to 28 the number of dead animals to have been found at the estuary in Brittany since the beginning of July.
Local campaigners are convinced the animals were suffocated by toxic fumes from the decaying green algae that has already closed the beach.
“What we are seeing in Brittany at the moment in many stretches of fresh water are cultures of bacteria, certain types of which are toxic.” said Gilles Huet from the Brittany Water and Rivers Association.
The campaigners say agricultural run-off is what causes the algae to grow.
The authorities, though, say they don’t know what is killing the animals and insist tests are being carried out.