'Leaky holes' have reportedly been found in the word filters that mainland online services are supposed to install to censor Internet content.
The report in the Beijing Entertainment News was a rare official acknowledgement that the government requires online information to be filtered.
Internet analysts say the government uses so-called 'packet sniffers' to monitor Internet use, blocking sites that contain sensitive combinations of words.
'It's interesting that it's in the media and it's okay to talk about,' said Nathan Midler, Asia-Pacific senior analyst with IDC.
'Articles like this mean the word will get out, and people will see it's actually happening. A small minority will start to understand what's going on and quietly complain.'
The Beijing Entertainment News report said government inspectors checked the compliance of online companies and cyber-cafes last week. Officials at mainland portal Sina.com said they used filters to keep 'harmful content' from bulletin boards and suspend displays of pages containing the wrong words.
The use of these filters had been required for about two months, Mr Midler said, starting at about the time the Google.com search engine was blocked.