The Japanese Transport Ministry has found Mazda Motor Corp, Suzuki Motor Corp and Yamaha Motor to have conducted improper fuel economy and emissions tests on their vehicles, as per a report by Reuters.

According to the report, this is the latest episode in a growing list of data falsifications in Japan, which it says has tarnished the image of the country’s manufacturing industry, known for its high-quality and efficient production.

The findings are part of the results on the back of internal investigations ordered by the ministry on the Japanese automakers, after it had found discrepancy in testing at Subaru Corp and Nissan Motor Co earlier.

Meanwhile, Japanese newswire Kyodo says the Transport Ministry had directed 23 Japanese automakers last month to conduct in-house investigations after Nissan Motor Co and Subaru Corp admitted they falsified data on emissions or fuel efficiency during the final checkups on their products. Suzuki President Toshihiro Suzuki and senior Mazda officials will respectively hold press conferences later in the day, the companies said.

Suzuki, Mazda and Yamaha Motor treated emissions or fuel efficiency data on vehicles as effective even though there were failures in their testing results, the ministry said. For Suzuki, data on almost half of its nearly 13,000 units manufactured between June 2012 and July 2018 were improper. The ministry made the results public based on reports by 20 automakers collected as of Wednesday.

"It is extremely regrettable. The ministry will strictly instruct the carmakers to make sure thorough preventive measures are taken," transport minister Keiichi Ishii said in a released statement, as per the Kyodo report.

The report says the representatives for Mazda and Suzuki have confirmed they submitted reports regarding improper testing to the ministry but declined to comment further, while Yamaha Motor confirmed it carried out inappropriate testing. Speaking to Reuters, a Yamaha spokesperson said, “Regarding the emissions inspections... it is a fact that there were improper actions. We sincerely apologise.”

According to a report earlier in July this year, Nissan admitted it had improperly measured exhaust emissions and fuel economy for 19 vehicle models sold in Japan.