SHANGHAI, Sep. 1 -- THE government has ordered Chinese search engines to remove illegal and unhealthy information from their search results, the Ministry of Information Industry said yesterday.

The Websites, including Google China, China Yahoo and Baidu.com, will have to clean up their results within a week, Xinhua news agency reported.

They should map out a procedure on how to dispose of illegal information, how to manage content and how to deal with users' complaints, the ministry said.

No definition was given to specify what is considered illegal or unhealthy content.

A ministry official who only gave his surname as Wang said pornography was one kind but refused to clarify more.

"The search engines know what they should do," Wang said.

China's press and publication regulator kicked off a campaign to close pornographic Websites earlier this month.

The regulator also ordered all Websites to delete 40 pornographic novels that it had blacklisted or the operators would be punished.