The rule, which obliges labourers on public construction sites to speak French while on the job, targets foreign companies that hire cheaper workers from elsewhere in the European Union (EU).
“This clause is necessary and targets foreign companies who come with their teams, without any of them speaking French,” said vice president of the region Jérôme Chartier. “These companies need to improve."
The so-called Molière clause, named after the seventeenth-century playwright, will also oblige firms working on publicly-funded building projects to use French as their working language.
Proponents of the measure say it will improve the employment opportunities and conditions of local workers, as it will be more difficult for contractors to temporarily bring in “cheaper” workers from foreign countries to do the job.
Supporters also say it will boost the regional economy, as one of its aims is to award more local public contracts to small French businesses.
But opponents argue that the clause is discriminatory, and puts newly arrived foreign workers in France at a disadvantage.
Other French regions, such as Normandy and Auvergne-Rhône-Alpes, have already introduced similar rules.