The firm's board is investigating chairman Zhu Gongshan and his son, company director Zhu Yufeng, over their holdings in two cogeneration plants in China.
The board launched the investigation in response to a 22 August enquiry by the Hong Kong stock exchange.
It said Zhu Yufeng purchased a cogeneration plant and a 9% stake in another facility in Jiangsu province in 2008.
He
