A former party chief of Yunnan province and two high-ranking Shanxi officials are under investigation for corruption - the latest targets of an anti-graft campaign launched by President Xi Jinping.
The Central Commission for Discipline Inspection said Bai Enpei, 68, Yunnan party secretary from 2001 to 2011, was suspected of "having seriously violated discipline and law", a term that usually refers to graft.
Before governing Yunnan, Bai spent 20 years in Shaanxi and Inner Mongolia, and was Qinghai governor and party boss in the late 1990s.
He was nominated as deputy head of the environment and resource protection committee of the National People's Congress in August 2011.
Bai was implicated in the case of Liu Han, a Sichuan mining tycoon with links to disgraced former security tsar Zhou Yongkang . Liu was sentenced to death in May for leading a mafia-style gang.
The commission also announced that Bai Yun, a member of the Shanxi party leadership's standing committee and director of its United Front Work Department, was being investigated for the same offence.
Shanxi vice-governor Ren Runhou was also facing investigation, the anti-graft authority said. Ren has spent most of his career in the province's coal sector.
Ren and Bai Yun join seven other provincial leaders in coal-rich Shanxi who have fallen from grace this year. Jin Daoming, deputy director of the provincial people's congress standing committee, and Luliang mayor Ding Xuefeng were held for corruption.
Investigations into another Shanxi vice-governor, Du Shanxue, and Ling Zhengce, vice-chairman of the province's political advisory body, were announced in June.
Ling's brother, Ling Jihua, was a key aide to former president Hu Jintao and seen as a rising star until he suffered a setback two years ago when he was alleged to have covered up his son's death in a Ferrari crash.
Xie Kemin, former deputy commissioner of Shanxi's discipline inspection commission, was expelled from the party and fired for graft. Rounding off the list of graft suspects are party committee secretary Nie Chunyu and Chen Chuanping, secretary of the Taiyuan municipal committee.
Since Xi came to power, coal-rich Shanxi has had more provincial standing committee members investigated for graft - six - than any other province.