Lei Jie, chairman of China's Founder Securities Co and its joint venture with Credit Suisse Group AG, could not be contacted by Founder as the government questions executives at the company's parent.

Lei asked for a week's sick leave on Jan 12 and the firm has not been able to reach him since Monday, Founder Securities told Shanghai's stock exchange on Thursday night. Lei could not be reached on his mobile on Thursday.

Founder Securities, China's sixth-largest listed brokerage, and parent Peking University Founder Group are embroiled in disputes with billionaire Miles Kwok's Beijing Zenith Holdings Co, the brokerage's second-largest shareholder. In a public trading of accusations since late last year, Founder denied Zenith claims ranging from insider trading to misappropriating State assets.