The Chinese government has clamped down further on social media in an effort to stop the spread of online rumours that could threaten its grip on power following the spectacular downfall of Bo Xilai, the former Chongqing Communist party boss.
Sina Weibo, China's largest microblog service, has shut four accounts that it claims were used to spread rumours in response to pressure from government censors. The Chinese internet has been rife with rumours – including one about a possible military coup – since the party ousted Mr Bo and revealed that his wife had been arrested on suspicion of murdering British businessman Neil Heywood.
The Bo scandal, which has sparked the gravest crisis for the Communist party since the Tiananmen massacre in 1989, has fuelled online discussion about a power struggle at the top of the party.
Rumours about battles at the top of the party as China prepares for a generational leadership change have travelled faster on the country's wildly popular Twitter equivalents, including Sina Weibo and Tencent Weibo, than censors can react.
Sina told Weibo users that "lawless elements" who had spread "vicious political rumours" over the service had already been "dealt with" by the police, and that it had closed four accounts of people accused of spreading rumours.
"Sina Weibo calls on the many internet users to consciously abide by laws and regulations, not to pass on rumours, not to believe in rumours, to report it immediately when rumours are being spread, and to work together to protect a healthy internet environment and good social order," the company said.
Sina did not respond to requests for comment. The move is seen as a sign of nervousness as Beijing has failed to stop netizens from exchanging information and views about alleged corruption, abuse of power and factional struggles in the party.
Reports published on dissident websites overseas, such as Boxun, that are beyond the reach of Chinese censors, have been spread widely in China over Weibo.
One of the accounts that Sina closed belonged to Li Delin, a financial journalist who tweeted last month that large numbers of military vehicles had been seen in the capital in the wake of Mr Bo being ousted.
Mr. Li's post sparked rumours of a coup, although he later posted another Weibo message denying that he had sent the original post himself and claiming that his account had been hijacked.
His last Weibo message contained a table comparing the political ups and downs in the former Soviet Union and Communist China – a timeline that ends with the demise of the Soviet Union and invites discussion about the future of Communist party power in China. Mr. Li has been unaccounted for since March 25, said a source familiar with the situation.
Wu Guancong, a Guangzhou-based entrepreneur who owned one of the closed accounts, was detained in Guangzhou on March 25, according to his lawyers. They said Beijing police brought him to the capital two days later, and that he has not been heard from since.