Sanofi said on Monday that it had stopped production at the plant after an environment body filed a complaint against what it said was massive air pollution.

France Nature Environnement, a federation representing some 3,500 local associations, said emissions at the Mourenx plant, which produces the epilepsy treatment valproate, had been 7,000 times above the limit allowed by French law.

(Reporting by Sudip Kar-Gupta; editing by Jason Neely)