BEIJING ��" China's Twitter-like websites are facing new threats of censorship.One of the country's top microblogs is down for maintenance, and the other three have begun displaying a "beta" tag to indicate they are in testing, though they have been operating for months. Users worry that the changes are cover-ups for further restraints on speech in China, where Twitter itself is blocked. They have deluged Chinese cyberspace and the microblog operators with questions and theories about the changes. Long Weilian, a China-based tech blogger who uses the name William Long, was skeptical about China's top four microblogs suddenly posting "beta" tags or going "under maintenance." "Such a long time to figure that one out," he tweeted Wednesday. Chinese officials often fear that public opinion might spiral out of control as social networking - and social protests - boom among the world's largest Internet population. The government unplugged Twitter and Facebook last year but has allowed domestic versions to fill the void while keeping them under scrutiny. Microblogs can quickly aggregate opposition voices, which is why authorities have been increasing controls, said Xiao Qiang, director of the China Internet Project at the University of California-Berkeley. "However, given the speed and volume of microblogging content produced in Chinese cyberspace, censors are still several steps behind at this stage," he said in an e-mail. China's government actually embraced microblogs earlier this year, with the Communist Party newspaper, the People's Daily, launching a microblog of its own. Delegates to the annual National People's Congress were encouraged to use microblogs to report on the meetings. The People's Daily microblog showed no sign Thursday of new restrictions. But the Netease.com Inc. microblog was down for maintenance, while the Sina Corp., Sohu Inc. and Tencent microblogs displayed a beta tag. Over the weekend, Sohu's microblogging service was down completely. Otherwise, the sites were allowing search and other functions Thursday. Some company officials hurried to reassure the public. Sina president Chen Tong responded Wednesday night to speculation that the site could be shut down. "Of course not," he said on the site's microblog. "I've said that sentence more than any other one today." Government officials could not be reached for comment. The telephone at the news office of China's Ministry of Industry and Information Technology rang unanswered. A Tencent spokesman told the China Daily newspaper that the beta tag had been on the site's front page since April. A Sohu spokeswoman did not respond to questions, and spokesmen for Sina and Netease could not be reached. China maintains the world's most extensive Internet monitoring and filtering system for its 420 million users. As part of that, Internet companies are required to censor online content to expunge lewd remarks or pointed political comment. Google's refusal to continue censoring search results was one of the reasons it moved its Chinese search engine offshore earlier this year. In another possible move against microblogs, Wang Chen, director of the State Council Information Office, has called for requirements that people use their real names when going online. Microblog users don't need to use their real names to register.
