Yang Xiaobo, former mayor of Gaoping, Shanxi province.[Photo/Baidu.com]

Li Chengyan, a researcher with Peking University, told the Beijing News the rise in female officials' graft cases is simply a result of gender parity in senior governmental posts, stronger anti-corruption forces and the overall increase in corruption cases.

"Corruption has nothing to do with age and gender," Li said. "It has to do with loopholes of legal supervision on power, and how power should be restrained accordingly."

Even so, female officials have drawn attention for distinctive characteristics in their abuse of power cases. For example, there has been speculation that they traded sex for power or accepted bribes to satisfy a desire for the high life.

Public debate speculated as to whether Zhang and Yang were involved in "sex-for-power" deals. The China Economic Weekly cited sources as saying Yang has had improper relations with senior officials.

The Beijing News reported that Zhang was a former colleague of Jin Daoming, former deputy director of the Shanxi Provincial People's Congress Standing Committee who was placed under investigation on Feb 27 for what officials described as a "grave violation of discipline and law". Jin was removed from office in March.

Zhang, 49, started working at the Shanxi Discipline Committee in March 2000, and became a standing member of the committee in October 2006, two months after Jin was appointed as committee secretary. They worked together for seven years before Zhang was transferred to Jinzhong.