Nearly 200 internet cafes have been closed down by the authorities in China's second largest city, Shanghai.
The latest clampdown targeted unlicensed cafes in the suburbs, the state-run Xinhua news agency said.
One official said the premises were in areas overlooked in previous campaigns.
The move is reported to coincide with the launch by the central government of a drive against "harmful" content on the web, to prevent young people from being corrupted.
Correspondents say the move underscores the government's desire to encourage the internet as a commercial medium without creating a forum for political dissent.
Communist Party officials have also suggested there is a growing trend for "illegal activities" to take place online.
Beijing requires internet bars to install software to block restricted web sites and record user activities.
According to one survey, China's home internet is second only to the US
Last year, the Chinese authorities reportedly shut down 17,000 internet cafes that failed to install the necessary software, the Associated Press news agency said.
Banned websites include those run by democracy activists, outlawed groups such as Falung Gong, and some foreign news organisations. Those containing pornographic material are also blocked.
According to government figures, about 30 million of China's 1.3 billion people now log on to the internet.
Called "wang ba" or "net bar" in Mandarin, internet cafes have sprung up in almost every Chinese city and many large villages.
The majority, however, are just one-room shops with personal computers.