"At first, we thought it was merely a game for a few mentally abnormal people," the paper quoted Liu as saying. "But as our research continued, we found the problem was much larger than expected."
Participants in the sites download chat software and attach video cameras to their computers, the paper reported. They then "talk with others while exposing themselves and performing provocative poses," it said.
Liu said he gathered data on 10 site participants, eight of whom were single men aged 25-35 without steady jobs and two women, it said.
China has tightened policing of the web following alarms over blogs, chat rooms, and instant messages that have challenged restrictions on content.
China has more than 87 million internet users, the second largest after the United States.