Authorities have ordered all China-based Web sites and blogs to register or be closed down, in the latest effort by the communist government to police the world of cyberspace.

"The Internet has profited many people but it also has brought many problems, such as sex, violence and feudal superstitions and other harmful information that has seriously poisoned people's spirits," the MII Web site said in explaining the rules, which were quietly introduced in March.

"There's a 'Net Crawler System' that will monitor the sites in real time and search each Web address for its registration number," said one document listing questions and answers about the new rules. "It will report back to the MII if it finds a site thought to be unregistered."