China's biggest digital entertainment and gaming expo is to impose exorbitant fines on scantily clad models and may be calculated by centimeters of exposed breasts, in the latest sign of China's efforts to improve social morality, news website thepaper.cn reported.

ChinaJoy, a huge trade fair that also features conventions for fans of manga and cosplay, has become well known since its debut in 2004 in Beijingfor the huge number of (mainly female) models dressed as characters from Japanese anime stories to promote online gaming and other digital entertainment. The event, held in Shanghai every July since 2005, has been described as an "exhibition of flesh".

There will be none of this kind of "vulgarity" on display at this summer's event. Pictures uploaded to Sina Weibo, China's version of Twitter, show a document issued by ChinaJoy organizers detailing examples of improper employee behavior and dress, along with fines for each indecent act or costume choice.

The fines will start at 5,000 yuan (around $800) for models who wear only bikinis, or whose tops reveal more than 2 centimeters of cleavage. If their trousers or skirts reveal their hip bones, or begin more than two centimeters below their navels, they will face similar punishment. Other banned items included miniskirts that reveal buttocks or transparent clothes through which underwear is visible, while anyone not wearing underwear at all will be fined 5,000 yuan.

Male models who appear topless, wear only underpants or reveal their hip bones will have to pay the same amount, it was reported. The stiffest punishments, however, are reserved for anyone taking part in pole or cage dancing - and for models who "assume vulgar poses" or become "over-intimate" while posing for photographs with members of the public. Such infractions will incur a fine of 10,000 yuan (around $1,600).

A spokeswoman for New Silk Road Fashion, an agency hired by the ChinaJoy organizer to vet model agencies, confirmed the news to thepaper.cn.

Many netizens are still deeply saddened by the prospect of ChinaJoy losing its "best" parts. "Without breasts, why the hell would anyone go to ChinaJoy?" one netizen wondered.

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.