French authorities are investigating carmaker Renault for suspected fraud over its diesel emissions controls.
The move dented the company's share price as the global fallout spreads from revelations of emissions cheating at Volkswagen.
Renault insisted that its cars are not equipped with pollution cheating software and that the company complies with all French and European laws.
Shares in partially state-owned Renault - one of France's leading manufacturers - dropped 4% on Friday but later recovered to trade 1.6% lower.
The Paris prosecutor's office said three investigating judges have opened a judicial inquiry into Renault's emissions controls practices and whether they "made merchandise dangerous for human health".
The probe is based on an initial investigation by the economy ministry's fraud department, which handed its findings to prosecutors in November.
French authorities raided Renault company premises after Volkswagen was found to have used engine software to cheat on US diesel emissions tests.
Renault recalled 15,000 cars last year because they spewed out excessive levels of harmful gases, but the company insisted there was no intentional wrongdoing.
Renault-Nissan chief executive Carlos Ghosn has said that despite the Volkswagen scandal, the company will continue developing diesel technology, particularly for SUVs and other high-end cars.
In a statement, Renault took note of the investigation but said its "vehicles are not equipped with cheating software affecting anti-pollution systems".
It said the company supports European moves to toughen emissions testing and has taken steps to reduce its own cars' emissions over the past year.
French prosecutors are carrying out a separate probe into Volkswagen's emissions practices in France.
Tentacles of the Volkswagen scandal are continuing to reach across the industry more than a year later.
The US government accused Fiat Chrysler on Thursday of failing to disclose software in some vehicles that lets them emit more pollution than allowed.