The French carmaker – Renault said that law enforcement agencies have inspected three facilities of the company to verify the emissions technology in its vehicles.
Renault's market value fell billions of euro amid the scandal that engulfed its German rival - Volkswagen.
Renault said that the investigation did not find "any evidence that Renault cars have some software reporting incorrect information on emissions" - alluding to the program software, which, as US investigators found, Volkswagen has used to bypass checks for harmful emissions.
Renault shares fell 22 % after the union representatives first reported on the searches, and the company had to issue a statement confirming the verifications.
In the past, Volkswagen has admitted to using software for underreporting the level of toxic emissions in a number of diesel vehicles in the United States.
The French company has lost about 5 billion euro of market price on Thursday, having survived the worst day of trading since 1994, according to Reuters data. The decline consisted in 20 % on Thursday. "It's hard to believe that Volkswagen is only one company which avoided checking for harmful emissions," - said Ion-Marc Valahu of Clairinvest.
As of the end of December, there have been tested 4 of 11 models of Renault, and there was not found any evidence of fraud, the company said.
Nevertheless, the investigators "have decided to hold an additional check of components and plants in order to accurately confirm the initial analysis of the independent technical commission", - said in a statement Renault.
French Finance Ministry declined to comment.
The Energy Minister, Segolene Royal, said that tests conducted showed no signs of presence of software distorting emissions in Renault.
"The Renault is not cheating. Shareholders and employees can be confident," - she told reporters.
But she added that cars of other companies recorded elevated levels of harmful emissions.