China regularly blocks sites it finds unsavory, particularly those related to Tibet or critical of the Communist Party.
It considers self-ruled Taiwan as a breakaway province that must be reunited with the mainland, by force if necessary.
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, according to a report by Asiaweek this week. They remained blocked on Tuesday.
"We can't deny that some websites continue to have problems that violate Chinese law," foreign ministry spokesman 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.
"We hope that the relevant websites can comply with China's concerns and not do things contrary to Chinese law. This will help establish a good cooperation between China and the relevant countries, as well as China and the relevant websites."
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.
Asiaweek's first front cover in December features an article on taxi strikes that broke out recently across China. Its latest front cover is a tribute to volunteers during the Sichuan earthquake, which killed about 80,000 people.