An emerging scandal concerning a major Japanese steel manufacturer is set to have a major impact on automakers. Over the weekend, it was reported that Kobe Steel acknowledged it had fabricated data about the quality of the aluminium and copper it had provided to clients, which included a number of automakers.

It was revealed that inspection certificates of flat-rolled and extruded aluminium as well as copper products – shipped between September last year to August this year – were altered or falsified to match requirements specified by customers, The Nikkei reported. Apparently, dozens of employees were involved in the misconduct.

The company, which supplies materials to a wide variety of industries, including those involved in the manufacture of aircraft, bullet train and cars, did not divulge who its clients were, but said that the issue – which might trace as far back as a decade ago – could involve products sent to as many as 200 companies.

On the automotive front, Japanese automakers said that they were using material from Kobe Steel in their vehicle production and were currently investigating the issue.

Toyota said that Kobe Steel materials have been used in hoods, rear doors and peripheral areas in its vehicles, but added that the issue was limited to its plants in Japan and that factories in other countries weren’t affected. Likewise, Honda said the materials in question had been used in the construction of doors and hoods for its cars.

Subaru said it had vehicles that used the contentious aluminium and was checking whether that use affects safety. This was echoed by Nissan, which said it was looking into the material’s potential impact on vehicle functionality.

Mazda said it also used aluminium produced by Kobe Steel and was in the process of checking which vehicles it was used in, while Mitsubishi stated it was in the midst of confirming affected models.

According to the publication, the country’s transport ministry has called on the carmakers to identify models using any of the affected material and conduct safety checks on these to see if any recalls are necessary.