Hong Kong-based investment fund Oasis Management said Tuesday that it plans to file a damages lawsuit against the former chairman of Kobayashi Pharmaceutical and others over a high-profile health hazard scandal involving supplements containing beni kо̄ji red fermented rice.

In the shareholder derivative suit, the fund will seek a total of roughly ¥11 billion ($70.6 million) in damages from former Chairman Kazumasa Kobayashi and six others who were board directors when the issue came to light.

It argues that the then executives were responsible for the scandal and that they caused damage to the Japanese drugmaker, in which Oasis Management has a 10.1% stake.

The fund called on Kobayashi Pharmaceutical last November to file a damages suit against the former chairman and others, but the request was denied. It has described the company's refusal as being unacceptable.

Kobayashi Pharmaceutical said in a statement Tuesday that it has not confirmed that a derivative suit has been filed.

Oasis Management is boosting its efforts ahead of the drugmaker's extraordinary shareholders meeting on Feb. 19, proposing the appointment of outside directors.