PSA Group’s share prices fell after French newspaper Le Monde reported allegations that the manufacturer had used an emissions “defeat device” on two million vehicles sold between 2013 and 2015.

The publication reported that an investigation carried out by the Directorate-General for Competition, Consumer Affairs and the Prevention of Fraud (DGCCRF) into alleged emissions cheating by PSA Group had uncovered evidence of the software's use and, despite the denial of the use of any use of fraudulent engine software by the Paris-based manufacturer, Reuters reported that the group’s stock was down 4.4% at 17.78 euros this morning.

PSA is one of four vehicle manufacturers under investigation by the DGCCRF since February, including Volkswagen, Renault and the FCA Group.

Le Monde reported that an internal PSA document obtained by the DGCCRF had reference a need to “make the ‘defeat device’ aspect less obvious and visible”.

In response to press reports today, Groupe PSA said that it had not been contacted by the judicial authorities and stated that it was “outraged to learn that information has been provided to third parties whereas Groupe PSA has never had access to the file submitted by the DGCCRF to the public prosecutor's office, making it impossible for the group to put forward its arguments”.

Groupe PSA said that it had repeatedly explained its strategy regarding engine settings, a strategy which it said was based on its customers’ use in real life, favouring low NOx emissions in cities while ensuring the best NOx/ CO2balance on open roads.

In a statement issued today, PSA Group added: “This situation undermines the group’s reputation and the interests of its 210,000 employees, its customers and its partners.

“Groupe PSA reserves the right to file a complaint for breach of confidentiality of the investigation and the authorities’ confidentiality obligation.”