China's foreign ministry said on Tuesday the country was within its rights to block websites with content illegal under Chinese law.
China regularly blocks sites it finds unsavoury, particularly those related to Tibet or critical of the Communist Party.
Access to the Chinese-language versions of the ,BBC Voice of America and Hong Kong media Ming Pao News and Asiaweek has been blocked since early December.
"We can't deny that some websites continue to have problems that violate Chinese law," Foreign Ministry spokesperson Liu Jianchao said.
"For instance, if a website refers to 'two Chinas' or refers to mainland China and Taiwan as two independent regions, we believe that violates China's Anti-Seccession Law as well as other laws," he said.
China has the world's greatest number of internet users, allowing its citizens vastly increased access to information.
In response, the country has set up a team of personnel who police the internet to remove sensitive content and posts warn bloggers who cross the line and block access to certain sites.