Renault SA (RNLSY) shares fell sharply Wednesday after a report in France's Liberation newspaper said the carmaker is suspected of trying to disguise the true level of emissions from some of its diesel-powered vehicles.

The paper said that it had consulted documents from France's Directorate-General for Competition, Consumer Affairs and Fraud Prevention (DGCCRF) which concluded that "the company used a strategy aimed at distorting the results of antipollution tests."

"Important differences between the performance of certain Renault engines in the laboratory and their results under real conditions," were found, the paper said, adding the accusation forms the cornerstone of an investigation reportedly opened by French prosecutors in January. 

Renault shares were marked 3.2% lower in Paris at €82.58 each by 12:50 CET and have fallen more than 6% since reports of the emissions investigation first appeared on Jan. 12, compared to a 1.7% gain for the Stoxx All Europe 800 Automobiles & Parts Index.

Renault declined to comment directly on the report when contacted in Paris by TheStreet, but later published a statement via its media office.

"Groupe Renault has acknowledged the publication of an unbalanced national newspaper article related to the "emission" case," the statement said "This article alleges to quote selected excerpts from a report drafted by the DGCCRF."

"Groupe Renault will not comment on a current investigation, the latter being confidential by nature and Renault having as yet no access to the case. As a consequence, Renault cannot confirm the veracity, completeness and reliability of the information published in said article" the company added.