Mitsubishi Motors shares dived 15 percent in Tokyo Wednesday in response to reports that the Japanese automaker conducted improper emissions tests, in the wake of a massive pollution-cheating scandal at Volkswagen.

The company declined to comment on the reports in Japanese media but said it would hold a press briefing at 5:00 pm local time (0800 GMT).

Its shares plunged 15.16 percent to close at 733 yen ($6.73).