Since China began its crackdown on online pornography, around 15 thousand porn websites including 11,000 mobile WAP sites have been shut down or blocked.

China's Internet Information Center has checked more than 13 million domain names one by one and has blocked 15,000 porn-related sites. The center is requiring domain name registrars to strengthen supervision of applicants' information and regulate the registering process.

Anti-pornography and illegal publications departments say that two chains had formed centering on porn websites. One featured advertisers, service providers and Internet operators, their profits coming from the large number of visitors to the websites. The other included search engine providers, payment service providers and domain name registrars, with profits generated by the large volume of business.

Huang Xiaoxin from Anti-porn office, said, "Many porn sites used payment service platforms to collect money so as to hide their accounts."

Anti-porn departments have pointed out destroying the website chains is a key breakthrough in the fight against the spread of pornography.

Policeman Li Yongcheng said, "We must regulate service providers, advertisers as well as payment service providers so as to cut the porn website profit sources."

Internet use has expanded at a dizzying pace in China, which now has the world's largest online population with at least 338 million users.