China has blocked a number of foreign websites which were previously available during the Olympics, including the Chinese version of the BBC news site.
The Voice of America site in Chinese has also been blocked, reports the BBC.
These and other sites had previously been unblocked, after journalists attending the Beijing Olympics complained that the government was censoring sites deemed to be politically sensitive.
They have now been banned again. The Chinese government has refused to confirm that it was behind the censorship, reports the BBC.
The likes of Google, Microsoft and Yahoo recently announced they would be working together to form a code of practice when conducting web business in countries deemed to have poor human rights and freedom of speech records.
In the past, all three firms have pulled sites or handed over personal data at the Chinese government's request.