BEIJING - Five officials of north China's Shanxi province are being investigated, with two already removed from office, the Communist Party of China (CPC)'s discipline watchdog announced on Thursday.

The five include Wang Min, head of the discipline authority in Yangquan City of Shanxi and Wang Shuxin, executive deputy mayor of Jincheng City, both are investigated for "serious discipline and law violations," according to the CPC Central Commission for Discipline Inspection.

The announcement closely follows the fall of a number of senior officials in the coal-rich province in August, including vice provincial governor Ren Runhou and Chen Chuanping, Party chief of the provincial capital Taiyuan.

Shanxi is one of the major coal producers in China and contributes greatly to the country's energy supply. Huge coal output has also brought the province serious environment pollution and a booming economy.