In messages, the operators of Sina.com’s Weibo microblog detailed the suspensions of the bloggers. The announcements provoked a torrent of online protest, some of which was directed at the government on the assumption that it was behind the punishments.

If so, it was the clearest expression yet of the government’s growing concern about its inability to curb free expression on the Internet — particularly searing criticism of official acts — despite a sweeping and extremely sophisticated censorship regime.

On Monday, a member of the Politburo, the Communist Party committee that acts as China’s collective leadership, visited Sina.com officials and said that they should “resolutely put an end to fake and misleading information.” The official, Beijing’s party secretary, Liu Qi, said they should use new technology to better manage the microbloggers, whose numbers have grown explosively in the last year.

The company’s notices stated that two bloggers who had spread false rumors on Weibo would lose their right to post messages or to add followers for a month. One stated that a blogger had been suspended after posting a false report that the accused killer of a 19-year-old woman had been set free after his politically powerful father intervened.

Another disclosed the suspension of a blogger who accused the Red Cross Society of China, which is mired in a financial scandal, of selling blood at a profit.

Some Weibo users sardonically applauded the suspensions, writing that the notices of them spread the rumors more effectively than the original bloggers.

“I didn’t know about the story till now. How tragic!” one blogger wrote. Others expressed outrage. “How does Weibo know what’s true or not?” one user wrote. “Who gives Weibo the right to silence its users?”

Still, one official of a Chinese Internet-related service, speaking on the condition of anonymity about a matter of deep concern to the authorities, predicted that the notices would have a chilling effect.

The official said the announcements may also represent the start of further efforts to keep politically sensitive information out of the public domain. On Monday, People’s Daily, the Communist Party’s official newspaper, appeared to suggest that restrictions were in the works, publishing a full-page article on the “political mission” to control microblogs and other new forms of media.

Sina.com is not the only company feeling new pressure. The operator of China’s other major microblog, Tencent, received a July 19 visit from another Politburo member, Zhou Yongkang, who oversees public security. In a speech to Tencent employees, Mr. Zhou called for “greater self-discipline” to ensure that the Internet promoted social harmony.

The Chinese authorities have pursued two tracks with regard to the Internet, allowing freewheeling debate on topics unrelated to high-level politics and governance, but carefully monitoring — and sometimes banning — discussions on topics deemed too sensitive. Censors frequently notify users that a specific posting “was deleted according to relative laws and regulations.”

But official concern appears to have risen after two recent episodes demonstrated the potential power of the Chinese Web to mobilize social protest.

In the first, tens of million of online bloggers assailed government railway officials after a June 23 train crash near Wenzhou that killed 40 people, accusing the officials of incompetence, corruption and a cover-up. In mid-August, residents of Dalian in northeast China flooded microblogs with photographs of their protest against a local chemical factory, overwhelming censors’ attempts to delete the posts.

Since then, a welter of commentaries and articles in Communist Party newspapers have debated the need to rein in comments on the microblogs. The Chinese government abruptly blocked Twitter and Facebook in 2009. The services remain blocked today. But many analysts say that the government will not completely close the hugely popular microblogs for fear of a public backlash.

Mia Li and Shi Da contributed research from Beijing.

Article source: http://www.nytimes.com/2011/08/27/world/asia/27weibo.html?partner=rss&emc=rss