The Chinese government has launched a campaign to enforce curfews at Internet cafés before schools let students out on summer vacation, local media, quoted by an Associated Press report, said.
The focus of the weeklong crackdown "is to prevent the entry of kids under the age of 18," said a Culture Ministry official quoted by the China Daily newspaper.
It said violators could face penalties ranging from being shut down for 15 days to losing their license to operate.
Internet cafés are required to limit the hours that underage customers can spend online and only allow in a few minors at a time.
China has the world's second-biggest population of Internet users after the US, with 110 million people online, but tries to regulate what Web surfers can see online.
Rules on children in Internet cafes were imposed after Chinese officials warned that students were spending too much time playing online games and were getting access to violent and obscene material, the Associated Press report said.