A spokesman for China's Ministry of Foreign Affairs defended government censorship efforts that block access to some foreign websites, saying they had broken Chinese laws by promoting the idea that 'two Chinas' exist.

"I hope these websites will exercise self-discipline and not do anything that violates Chinese laws," said Liu Jianchao, a ministry spokesman, according to a transcript (in Chinese) of a Tuesday press conference.

His comments came in response to questions about Chinese access to websites like the BBC, Voice of America and others, being blocked again. Access to many censored websites was restored earlier this year, part of a government commitment to not restrict internet access during the Olympics. That grace period now appears to be over.

Prior to the Olympic games, China frequently blocked access to websites that it deems objectionable. The government rarely discusses these efforts, or provides information about why the websites are blocked.

Liu's comments suggest the reasons are largely political.

His reference to 'two Chinas' means Taiwan and China. China regards Taiwan as a renegade province, although the current Chinese government has never ruled the island. Taiwan is ruled by the Nationalist Party, which retreated to Taiwan in 1949 after losing the Chinese civil war to the Communists. The two sides have been locked in a military and political stalemate since that time.

Taiwan's political status remains a sensitive issue in China, and the government frequently speaks out against any politician or political statement that it believes supports the cause of Taiwanese independence, forbidden by China's anti-secession law.

Liu did not name the foreign websites that had allegedly fallen afoul of Chinese censors, but he defended China's right to manage Internet access according to its own laws.