The chairman of Group and its listed subsidiary Company, Mr Lei Yi is under investigation for alleged “serious disciplinary violations”, according to a company statement reported by Dow Jones.

Dow Jones noted that this phrase is frequently used in to refer to senior government or state company officials being investigated for corruption and was used by state media in May when a high-ranking official at ’s top economic planning body, the National Development and Reform Commission, was stripped of his post.

Yunnan Tin said vice chairman Gao Wenxiang has taken over the responsibilities of the chairman, and operations at the company remain normal.

Yunnan Tin has been the world’s largest tin producer for the last eight years, producing 69,760 tonnes of refined metal in 2012.