The largest global campaign against child pornography, in which China played a pivotal role, has been hailed a success.
Operation Angel, launched in April, has led to more than 250 arrests worldwide and blazed a trail in multinational operations, law enforcement officials said.
"Child protection is a global issue," said Yang Shaowen, deputy director of international cooperation for the Ministry of Public Security. "The campaign is a vital step for participating nations in protecting our youth."
Authorities in 20 countries and regions took part, targeting not only the people running illicit websites and host servers, but also those uploading indecent images.
Russell L. Hunt, legal attache for the FBI, spoke highly of the campaign and praised China's contribution in providing and analyzing evidence for investigations overseas.
Four websites were shut down, and police on the Chinese mainland detained more than 180 suspects in 30 provinces, with 19 more in the Hong Kong Special Administrative Region and 46 in Taiwan. The FBI arrested two people in the United States.
This month, Australian representatives said they had identified two suspects, while in Germany one man has been arrested and two more are under investigation based on evidence provided by the Chinese mainland.
New Zealand is also looking into one suspect.
"Investigations are still going on and we'll continue to provide help to other police forces," Yang said.
The FBI first contacted the Ministry of Public Security in September last year about suspected child porn websites that were hosted on servers in the US but managed in China.
A preliminary police investigation discovered 4 trillion bytes of child porn, including videos and photographs, on websites with more than 1 million members in more than 130 countries and regions.
Police in Operation Angel focused on suspects in 10 countries.
Chinese officials visited the US in November to discuss a joint probe, and it was agreed US authorities would supply raw data and Chinese police would offer analysis.
"Both sides also decided to launch a global law enforcement campaign against child porn," said Gu Jian, deputy director of Internet security for the ministry.
On April 17, police liaison officers from 20 countries and regions were invited to join the campaign.
It took just over a month for the first arrest, with Beijing authorities nabbing two suspects, identified only as Liu and Yang, on May 25.
Liu, 32, allegedly ran the website and had made 80,000 yuan ($13,000) from charging members to access and share obscene images.
Police said Yang, 28, owned the host Web server, although he has denied any involvement in child porn.
Both cases have been handed to prosecutors. Under Chinese laws, people who distribute obscene images face up to two years in prison.
Hamish McCardle, a police official with the New Zealand embassy in Beijing, said governments around the globe must work together to protect children.
"We must maintain a strong message to criminals: Child porn is wrong and the international police community will find you," he said, adding that the key to preventing such crimes is educating children, parents and teachers.
Wang Ping, managing director of the Chinese Society for Juvenile Delinquency Prevention Research, said child porn websites can cause people to imitate what they see.
"For some adults, the websites provide a platform for obscene behavior, and they also imitate what they see in uploaded pictures and damage children in real life," he warned.
China has an estimated 600 million Web users, and police handled 25,000 cases of online crime nationwide between June and September.
With cross-border crime soaring, Vice-Minister of Public Security Chen Zhimin said international cooperation is vital.
"Chinese police are very keen on joint investigations, such as Operation Angel," he said, adding that they not only catch crooks but also "establish trust among countries".
The ministry previously worked with the US to tackle obscene websites, and has reached agreements with other countries to cooperate on drug control, telecom fraud and terrorism.
This year, Chinese police arrested a major drug trafficker along the Mekong River with help from Laos, Thailand and Myanmar, and has cracked more than 6,000 telecom fraud cases with Southeast Asian countries, including Singapore and Malaysia.
China has established law enforcement partnerships with 83 countries and regions, Yang said.