U.S. agribusiness giant Monsanto said Tuesday it will appeal a French court ruling that found it responsible for the poisoning of a farmer who inhaled a weed killer, in the first such case to reach court in France.

A court in Lyon, southeast France, ruled Monday that Monsanto was guilty of poisoning grain grower Paul Francois, 47, who suffered from memory loss, headaches and stammering after inhaling the Lasso weedkiller in 2004.

The farmer accused the company of not providing adequate safety warnings on the product label.

"Monsanto is going to appeal this verdict. We are disappointed by the court's decision," Yann Fichet, head of institutional relations at Monsanto France, said.

"An in-depth examination of the case does not show in our view sufficient evidence of a causal link between the use of this herbicide and the symptoms reported by Mr Francois," he told France Info radio.

Francois said his health problems were caused by inhalation of Lasso while cleaning the tank of his crop sprayer. He blames Monsanto for not specifying on the label the presence of chlorobenzene, a chemical substance later detected in the farmer's hair and urine.

Lasso was banned in France in 2007 in line with a European Union directive.

The product has also become less popular with farmers elsewhere and Monsanto's leading herbicide is now Roundup, which it markets in conjunction with its genetically modified, weedkiller-tolerant "Roundup Ready" crops.

Monsanto's appeal in the French court case will take up to a year to be heard.