The corruption investigation into Shen Weichen, the former head of the China Association for Science and Technology, suggests the top leadership's anti-graft campaign is targeting officials with connections to the coal-producing province of Shanxi, according to analysts and political observers.
At least eight Communist Party officials from the resource-rich province have been detained for alleged "serious violations of discipline" this year, an expression that is often used to describe corruption.
Shen, aged 57, was formerly the top official in the provincial capital Taiyuan.
Others detained from the province include the vice-chairman of the People's Congress standing committee Jin Daoming and Ding Xuefeng, the former mayor of Luliang.
Sources said some of the detained officials were implicated in the corruption investigation into the former security tsar Zhou Yongkang.
Zhou has been in detention since December.
At least three sources said Ding was detained through his connections to Jia Xiaoye, Zhou's second wife.
Jia, born in Datong, Shanxi, in the early 1970s, married Zhou in about 2000.
Sources said Ding gave about 20 million yuan (HK$25 million) to Jia to secure the post as mayor of Luliang in 2012 before Zhou retired in that year's leadership transition.
It is not clear if Jia has returned the money since.
Ding knew Jia because he studied at the school where her father used to work, the sources said.
Others detained in Shanxi are connected with Ling Jihua, a native of the province and a close ally and aide of former president Hu Jintao.
Ling was demoted to head the United Front Work Department after the controversy surrounding his son's fatal crash in a Ferrari in Beijing in 2012. Ling is widely said to be the leader of a private group of senior officials and coal mining executives with links to Shanxi.
The group, called by some the "Xishan Club", is rumoured to have considerable political and economic power and it tried to help Ling reach the powerful Politburo before the party's once-in-a-decade transition of power in 2012.
"Shanxi possesses rich mineral resources and that resulted in rather serious collusion between a group of mining owners and some high officials," said Zhang Ming, a political scientist at Renmin University in Beijing.
"So officials and the business people there easily formed into a group that shared similar interests."
Zhang Lifan, a political analyst in Beijing, said many officials belonged to tight-knit groups and built their careers on them.