Renault referred to prosecutors over diesel emissions

(Adds detail, comment, background)

PARIS, Nov 9 (Reuters) - Renault (LSE: 0NQF.L - news) faces a criminal investigation over its diesel emissions after French officials passed a file to prosecutors detailing suspicions that the carmaker's engine technologies broke the law.

The French government said in a statement on Wednesday that the DGCCRF consumer fraud watchdog had sent prosecutors the findings of its enquiry into possible emissions test manipulation by Renault, which followed the Volkswagen (LSE: 0P6N.L - news) emissions scandal.

"It is now up to the courts to determine what further action to take over the suspected breaches," the government said. Officials at the prosecutor's office in Nanterre, west of Paris, were not available for comment.

Renault is so far the only carmaker after Volkswagen to be referred for possible criminal investigation in France. Renault (Swiss: RNO.SW - news) issued a short statement affirming that its engines complied with European law.

Following VW's exposure for using software to cheat U.S. tests, Renault and others have attracted scrutiny for their own use of "defeat devices" that reduce the effectiveness of technology that purges nitrogen oxides (NOx) from exhaust.

Such devices are calibrated to meet pollution standards during regulatory tests but not in many other conditions encountered on the road, when real emissions are allowed to soar. They are illegal except when deemed necessary to protect the engine - a European loophole that has been widely exploited.

Carmakers including Renault, Opel and Fiat (Hanover: FIA1.HA - news) told a separate French investigating committee earlier this year that defeat devices in their vehicles were legal under the exemption. But the panel concluded that their technical justifications "remained to be proven".

The findings now before prosecutors include material seized during police searches at Renault sites, interviews with company officials and results of independent testing carried out on Renault vehicles, an official with knowledge of the investigation said. The searches were reported in January.

The prosecutors are expected to carry out their own preliminary enquiry to decide whether to order a formal probe under an investigating judge, which can lead to a full trial.

Other unnamed carmakers remain under investigation by the DGCCRF, the government said in its statement.

(Reporting by Laurence Frost; editing by David Clarke and Susan Fenton)