China's domestic security chief, Zhou Yongkang, added his voice to calls for tighter Internet controls as censors ratcheted up temporary online restrictions, a day after a failed attempt to use social-networking sites to start a "Jasmine Revolution" in China...Despite the role of Twitter and Facebook Inc. in mobilizing protests in Egypt, Tunisia and elsewhere, China is, for the moment, allowing Chinese social-networking sites to flourish—provided they cooperate with censors... China's Internet censors have demonstrated a highly sophisticated capacity to control the flow of information online...—mainly by obliging Internet companies to remove politically sensitive content...[On] Sunday, after the anonymous appeal for a "Jasmine Revolution" in China appeared on a U.S.-based Chinese-language website and began to be circulated...[all] references to the appeal were deleted from Chinese sites and searches for "Jasmine" and related words were blocked on search engines and microblogging sites...The search function on Sina Weibo [part of Sina], one of the most popular microblogging sites, was disabled...Qiao Mu, director of the Center for International Communications Studies at Beijing Foreign Students University, said Sina Weibo appeared to be deleting more posts since President Hu's speech Saturday calling for tighter Internet controls. [also refers to Renren.com]