Mazda Motor Corp and Suzuki Motor Corp conducted improper fuel economy and emissions tests on their vehicles, the latest in a series of compliance scandals in Japan's auto sector, the Nikkei business daily reported.
Mazda and Suzuki have submitted reports of their findings on their tests to the transport ministry and will publicise details on Thursday, the Nikkei said.
Representatives for Mazda and Suzuki told Reuters they had submitted reports to the ministry but declined further comment.
Mazda shares were down 1.4 per cent and Suzuki down 3.4 per cent in early trade, versus a 0.4 per cent fall in the benchmark Nikkei.
