"The boom of pornographic content on the Internet has contaminated cyberspace and perverted China's young minds." said Zhang Xinfeng, vice minister of MPS.

In the next six months, Zhang said, the ministries will crack down on illegal on-line activities such as distributing pornographic materials and organizing cyber strip shows, and purge the web of sexually-explicit images, stories, and audio and video clips.

The campaign will also target on illegal on-line lotteries and contraband trade, fraud, and "content that spreads rumors and is of a slanderous nature", said Zhang.

In November 2006, Chinese police cracked the largest pornographic website in the country and arrested the creator Chen Hui, who was later sentenced to life imprisonment.

The website Chen started contained more than nine million pornographic images and articles and it had attracted more than 600,000 registered users.

"The inflow of pornographic materials from abroad and lax domestic control are to blame for the existing problems in China's cyberspace," Zhang said.

China has roughly 123 million Internet users, most of whom are young people. The Chinese government believes they need to be protected from negative on-line influences.

A report by the Beijing Reformatory for Juvenile Delinquents said 33.5 percent of its detainees were influenced by violent on-line games or erotic websites when they committed crimes such as robbery and rape.