French Ecology minister Segolene Royal ordered tests on a random sample of about 100 diesel cars last year after Germany's Volkswagen (>> Volkswagen AG) admitted that 11 million of its diesel vehicles had "defeat devices" which allowed them to meet emissions rules in test conditions.

"Tests conducted in France on 52 vehicles from 15 different brands showed no cheating device. However, the tests highlighted significantly higher emissions (in CO2 and Nox) in real traffic conditions," the Ecology ministry said.

The ministry said the vehicles that had failed to comply fully with French emissions regulations were made by Renault (>> Renault), Fiat , Mercedes, Volkswagen, PSA Peugeot Citroen (>> PEUGEOT), Nissan (>> Nissan Motor Co Ltd), Opel (>> General Motors Company) and Ford (>> Ford Motor Company).

(Reporting by Matthias Blamont; Editing by Alexander Smith)