Chinese authorities have blocked access to the video-sharing Web site YouTube -- the latest victim of a politically motivated Internet crackdown.
Authorities in Beijing have not explained why the site has been targeted for censorship.
There is widespread speculation, however, that YouTube has been targeted because of a video showing Chinese police taking violent measures against Tibetan protesters.
The footage was compiled from protests that occurred in March 2008, as well as during anti-Chinese riots that took place in the Tibetan capital of Lhasa in 1988.
It was uploaded to YouTube by Tibetans living in exile overseas.