The government made the move in an attempt to control the Chinese public's access to information following the outbreak of protests against Chinese rule in the Tibetan capital Lhasa on Friday.
YouTube can usually be accessed in China but it was blocked after videos of foreign news reports about the protests were posted on Saturday. In contrast to Pakistan's recent censorship of YouTube, China has blocked the entire site and not just a number of specific videos.
A number of videos opposing the protests in Tibet have also appeared on YouTube, with a video entitled "Tibet WAS, IS and ALWAYS WILL BE a part of CHINA" featuring on today's most viewed list. There have also been a number of angry posts from Chinese bloggers criticizing the West's portrayal of China and the protests in Tibet.
Use of the Internet for educational and business purposes is encouraged by the The Chinese government. But Internet access is censored by online filters which block any material considered to be politically subversive or obscene.
China is believed to have the largest number of Internet users on the planet, 210 million even though internet penetration is at 16.9% compared to 69.7% in the US.
CNN reports on protests in Tibet