In the latest round of talks on a new nationwide labor deal, Renault managers asked unions to sign up to an average 6.5 percent increase in working time, the carmaker said.
"This would contribute towards making French factories more attractive for the allocation of (production) volumes in addition to Renault's own output," Renault said in a statement.
That could include models for 43.4 percent-owned Japanese affiliate Nissan or German premium carmaker Daimler, a company spokeswoman added.
Renault's Maubeuge plant in northern France currently builds the Mercedes Citan delivery truck for Daimler. However, after nearly 14 years since the creation of the Renault-Nissan alliance the two partners have yet to share car production anywhere in Europe.
Domestic unions are being asked for an increase in working times to 35 hours a week, the statutory norm across French industry, Renault said. Pay for the extra hours will be addressed in later rounds of negotiations.
Last September the carmaker said it was seeking a new nationwide deal on pay and conditions to cut costs and align productivity with cheaper European sites such as its Palencia plant in Spain and Nissan's Sunderland factory in England.
Renault has previously dangled the prospect of guarantees on keeping its French plants open in negotiations with unions and warned that the outcome of talks would affect production, a negotiating stance denounced by some unions as "blackmail".
Editing by Greg Mahlich