FILE PHOTO: A monitor showing the logo of Mitsubishi Materials Corp is seen in Tokyo, Japan, November 24, 2017. REUTERS/Toru Hanai

TOKYO (Reuters) - Japan's Mitsubishi Materials Corp 5711.T on Monday announced a top management reshuffle after the maker of metals and other products for the first time explicitly accepted responsibility over a data tampering scandal dating back to last year.

In a statement, Mitsubishi Materials said its president Akira Takeuchi will step down from that role and assume the position of chairman after an annual shareholders meeting on June 22. Current executive vice-president Naoki Ono will take over from Takeuchi as president, a role that carries responsibility for executing strategy at Mitsubishi Materials.

The boardroom shake-up comes a few days after the firm said it had found fresh cases of misconduct at its Naoshima copper smelter and refinery in western Japan. The plant’s Japanese Industrial Standards (JIS) certification has been revoked.

That finding followed a company announcement a month earlier that it had found new cases of improper action at a small number of its group firms, widening the number of affected customers from 762 to an undisclosed figure.

The scandal is one of a series of quality assurance frauds to rock Japanese manufacturers. Since October, Japan has seen revelations of data tampering and compliance failures at Kobe Steel Ltd 5406.T, Toray Industries Inc 3402.T, Nissan Motor Co Ltd 7201.T and Subaru Corp 7270.T.

Shares in Mitsubishi Materials were up 0.2 percent as of 0545 GMT, underperforming the broader Topix .TOPX which was up 0.4 percent.