Two websites being used by tens of thousands of people to post weblogs (blogs) have been shut down by Chinese officials for carrying objectionable content–rumoured to be opinions on a letter from a well-known doctor to China's senior leadership asking them to reassess the 1989 Tiananmen Square protests.

The two sites–BlogBus, with more than 15,000 Chinese users, and Blogcn–have both been closed, at least temporarily.

Dr. Jiang Yanyong, who reported China's cover-up of the spread of SARS in 2003, asked the Communist Party's Politburo to reverse the official verdict that the student-led movement was a "counter-revolutionary rebellion." His letter was leaked to journalists in early March. Popular Chinese portals, including Sina, Sohu, and NetEase, patrol their sites for "politically incorrect" statements and delete such comments.

Last year, Chinese netizens were blocked access to the U.S.-based "Blogspot" Web site.