A senior Communist Party School official in northwest China's Shaanxi Province is being investigated for suspected serious discipline violations after he became embroiled in a sex scandal, authorities said on Thursday.

The Shaanxi provincial discipline inspection commission of the Communist Party of China (CPC) has launched an investigation into Qin Guogang, vice president of the Party School of the Shaanxi CPC committee, over allegations of a sexual relationship with a female postgraduate in the school, commission sources told Xinhua.

Photos of a naked man resembling Qin appeared online late on Monday. According to posts in cyberspace, he maintained sexual relations with the postgraduate for more than a year with the promise of marrying her, only for he and his wife to later beat the student in a school office.

The photos were stills from a video shot on Aug. 13, 2013 in the residence of the postgraduate, said Qu Jianguo, the woman's lawyer.

The school suspended Qin from his post on Wednesday.