Nissan has released a statement confirming that it has found falsification of data on emissions and fuel efficiency for vehicles produced at its facilities in Japan, adding that "this misconduct" is "regretful".

The automaker said it had been “proactively carrying out comprehensive compliance checks of various parts of its operations” since the September 2017 discovery of “nonconformities in the final vehicle inspection process” at its Japanese plants.

As part of a check of exhaust emissions and fuel economy measurement tests within the final vehicle inspection process, Nissan said it discovered “misconduct" carried out for vehicles produced at its domestic vehicle production plants and those of affiliates, except Nissan Motor Kyushu.

This included the “performance of exhaust emissions and fuel economy tests that deviated from the prescribed testing environment” as well as the “creation of inspection reports based on altered measurement values”.

“Nissan understands and regrets the concern and inconvenience caused to stakeholders as a result of its kanken issues last year. Proactive initiatives to prevent recurrence of such issues have led to the discovery of this misconduct, for which the company is regretful,” the firm said in its statement.

“A full and comprehensive investigation of the facts outlined above, including the causes and background of the misconduct, is underway,” Nissan said, adding that it had hired a leading Japanese law firm to carry out an investigation centred on the causes and would implement “appropriate countermeasures” based on the results.

Following re-verification of “reliable log data”, Nissan confirmed that all vehicles produced, except the GT-R, conformed to Japanese safety standards and also that the Nissan vehicle-type approval average measurement values guaranteed the catalogue specifications for exhaust emissions.

Similarly, Nissan said it had re-verified log data to confirm that all models subject to sampling tests guaranteed the Nissan catalogue specifications for fuel economy, meaning there were “no errors within the fuel economy figures disclosed by Nissan”.

“Strict adherence to compliance is a top priority for Nissan’s management, and if issues are discovered, appropriate measures will be taken. Nissan is committed to promoting and enforcing compliance and awareness thereof in all operational areas.