Models at the ChinaJoy digital entertainment and gaming expo in Shanghai, Aug 4, 2014. [Photo/IC]

This isn't the first time that officials have instituted a moral campaign to cleanse ChinaJoy's image. In 2011, local government set strict limits on the number of showgirls and the amount of breast that could be shown. They even went so far as to ban bikinis and costumes that exposed more than two-thirds of a showgirl's back.

This year's rules, and the attempt to enforce them, appear to be the strictest yet.

They follow the first ban on female models at the Shanghai Auto Show in April.

Authorities earlier insisted that one Chinese TV drama series be re-edited because the female characters' costumes revealed too much cleavage and last year launched a high-profile campaign against prostitution in the southern city of Dongguan.