China has unexpectedly replaced the head of Sinopec, Asia's largest oil refiner.

Chen Tonghai resigned as chairman of Hong Kong-listed Sinopec, in which the state is the majority shareholder, for "personal reasons", the company and China's State-owned Assets Supervision and Administration Commission said. However, a media report posted on Chinese websites quoted Sinopec's parent company, China Petrochemical, as saying Mr Chen stepped down because of "serious breaches of discipline".