A French minister on Wednesday said he had asked custom officers to tighten checks on Titan tyres after the US company's CEO last month mocked France's work ethics.
"We have asked customs to enforce French law, in particular when it comes to tyres produced in conditions that sometimes does not respect environmental and technical norms," Industrial Renewal Minister Arnaud Montebourg said.
"The message has been passed on. This is what I call law enforcement," Montebourg said.
Last month, Titan chief Maurice Taylor rejected Paris's invitation to invest in a loss-making Goodyear tyre plant, citing French business conditions, especially its wages and work ethics.
In his rebuff letter, Taylor said "the French workforce gets paid high wages but only works three hours" a day.
The letter triggered an uproar in France, and Montebourg accused the American executive of stupidity.
"Your extremist insults display a perfect ignorance of what our country is about," he wrote, adding "be assured that you can count on me to inspect your tyre imports with redoubled zeal".
Montebourg has provoked controversy by threatening to nationalise facilities that foreign investors want to scale down.