BEIJING - Police have detained a local government official in Central China's Hubei province, who allegedly strangled his pregnant mistress before dumping the body in a river.

Local newspapers reported on Thursday that police investigations had found Yunxian county government's general office's deputy director Li Guangsheng is suspected of killing his mistress, Li Xiuli, after she demanded he marry her or give her 2 million yuan ($300,100). She was pregnant with twins.

The official has been removed from his post, the county Party committee's publicity office said on Thursday.

The 46-year-old official started a relationship with the 34-year-old divorced mother in 2009, local media reported.

It turned sour this summer, when the woman became pregnant and threatened to disclose the affair if Li Guangsheng, who is married and has a child, did not meet her demands.

On the morning of Nov 20, the woman stopped Li Guangsheng from departing for a business trip and argued with him in his car. He grabbed her throat and began choking her, police said.

That night, the suspect allegedly bound the unconscious woman with wire and put her in to a leather bag filled with stones. He drove 30 kilometers out of town to Duhe bridge, where he dumped the body into the river.

Local media said Li Guangsheng appeared calm after the killing and pretended to be the woman, using her mobile phone to send text messages to her boss to plead for a long break from work.

On Dec 8, a villager reported the discovery of a floating leather bag containing a woman's body, the reports said.

Police tracked the text messages and call logs in the woman's phone and quickly listed Li Guangsheng as a suspect. He reportedly confessed during interrogations, local media reported.

The official's colleagues voiced surprise that the "quiet" and "popular" man could be so cruel.

They said Li Guangsheng's behavior had not changed since the alleged murder, recalling he quietly read the newspaper and told jokes as usual.

The murder is the latest in a string of deadly scandals arising from government officials' affairs.

In 2007, Duan Yihe, former chairman of the Standing Committee of the People's Congress of Jinan, masterminded a car bombing to kill his mistress, who was 30 years younger than him, after she demanded he marry her.

In 2010, 48-year-old Xie Zaixing, former Party chief of Ouhai district, Wenzhou city, was sentenced to death for murdering Shao Songqiao, with whom he had maintained a nine-year extramarital relationship.

China Daily