A beekeeping cooperative in northern France has filed a legal complaint against German chemicals giant Bayer after traces of the controversial weedkiller glyphosate were detected in batches of honey, officials said Friday.

The head of the cooperative in the Aisne region, which represents some 200 beekeepers, said Famille Michaud, one of the country’s largest honey marketers, found the chemical in three batches supplied by one of its members.

“They systematically analyse the honey shipments they receive, and they found glyphosate,” Jean-Marie Camus said.

The weedkiller, introduced by the US agro-giant Monsanto under the Roundup brand name, is the most widely used in France, where President Emmanuel Macron has vowed to outlaw it by 2021.

It is suspected by some scientists of causing cancer, though the EU renewed the licence for glyphosate weedkillers last November despite deep divisions between member states.