The head of a French fishing federation has lodged a complaint against global food conglomerate Nestlé, after thousands of fish were found dead in a river in north-eastern France, reports the BBC.
Several tonnes of dead fish were reported in the Aisne river at the weekend, close to a Nestlé factory.
The deaths were due to a decrease in oxygen levels in the water, the local prefecture said on Tuesday.
Tests are being carried out to determine the origin of the pollution.
The dead fish were found near Challerange, 50km (31 miles) from Reims, the prefecture said in a statement.
"We have lodged a complaint against Nestlé France for pollution and violation of article 432.2 of the environmental code," said Michel Adam, president of the Ardennes Fishing Federation.