Renault cars (RobWilson/Bigstock.com)

Shares in French auto giant Renault plunged by 20 per cent on news that police have raided its facilities, before closing just over 10 per cent down.

The company confirmed that police wanted to check equipment at its plants.

Shareholders exhibited concern that Renault might be embroiled in an emissions data-rigging scandal similar to the one affecting VW, who was found by the US Environmental Protection Agency to be rigging emissions data in millions of its models.

Renault, however, said there was "no evidence" that emissions data has been rigged by the firm.

Fraud investigators are looking at how Renault uses exhaust emissions technology, according to the company.

In a statement Renault said that police "decided to carry out additional on-site and material investigations, in order to definitively confirm the first findings resulting from the analysis of the independent technical commission".

Investigators "went to the headquarters, the Renault Technical Centre in Lardy and the Technocentre in Guyancourt."

According to the CGT Renault union, police were targeting the firm’s engine control units, in investigations which were probably "linked to the consequences of the Volkswagen rigged-engines affair".

French Energy minister Segolene Royal said that government tests had not found any use of so-called 'defeat devices' within Renault.

19.73 per cent of Renault is owned by the French government, through its Agence des participations de l'État.

Governments and car makers around the world have been on alert since news of the VW diesel rigging scandal emerged in September last year.