The China International Comics Games Expo (CCG) brought in city government authorities Sunday to help crack down on illicit exhibitors after local media reported that some vendors were selling pornographic and pirated products, the event's organizer said.

The five-day event, now in its ninth year, is one of the premier expos for video game and animation producers in China. About 325 companies from both home and abroad have joined this year's event, as well as vendors of related merchandise. Some of the big names include Shanda Games, Walt Disney Co and Oriental DreamWorks.

About 134,000 people visited the expo in its first three days, according to the organizer. The event will run until Monday at the Shanghai World Expo Exhibition and Convention Center in Pudong New Area.

Although the expo was designed to help companies show off their latest products, some attendees used it as a platform to sell pirated video game discs, some of which featured pictures of naked women, and other racy products, according to a report on the news website xinmin.cn. Vendors were also found selling metal knives and swords, which is against the expo's rules.

The expo's contract with exhibitors requires them to follow the rules, but some vendors have found ways to work around them, said Zhang Wei, the organizer's press officer.

Some vendors have avoided signing the contract entirely by sub-leasing a portion of exhibition space from legitimate exhibitors.

The arrangement is mutually beneficial because it helps legitimate exhibitors reduce their costs from attending the event.

Zhang said most of the rule breakers are small business owners that make up about 20 percent of the expo's exhibitors.

The expo's organizer strengthened inspections during the first three days of the event, partially in response to the local media's reports, Zhang said. It urged exhibitors to put away their illicit products, but some continued to sell them after the inspections ended.

Zhang said the organizer will expel vendors that continue to sell illicit products. It brought in the city's cultural authorities Sunday because they have the ability to fine exhibitors that break the rules.

Some exhibitors were still selling knives and swords on the sly Sunday when approached by a Global Times reporter posing as a customer. An exhibitor surnamed He said he was selling 30 knives a day for 150 yuan ($24.44) each. Another exhibitor was selling mouse pads in the shape of a woman's breast.