Since mid-March, the Chinese government has closed 42 websites and has deleted over 210,000 Internet posts. Sina, a large Chinese Internet provider, said that it had shut down four weibo accounts, which are the Chinese equivalent of Twitter (News - Alert) accounts.

One of the owners of the closed accounts, writer Li Delin, has reportedly disappeared.

“Recently, some lawbreakers have made use of weibo to without reason fabricate and spread malicious political rumors, producing a bad influence on society,” said Sina in a statement to its users. The provider also said that the four cases of closed accounts had been handed over to officials to be prosecuted “under the law.”

China started its latest broad Internet crackdown after the dismissal of political rising star Bo Xilai from his post as Communist Party chief of Chongqing. Bo was dismissed from his post after his chief of police fled to the United States consulate and demanded political asylum. According to online rumors, supporters of Bo tried to stage a coup after his wife was arrested in connection with the murder of a British national.

Immediately after the coup rumors began to spread, China shut down 16 websites and arrested many people in connection with the rumors. Sina and another Internet provider, Tencent, stopped microbloggers like weibo users from commenting on one another’s posts for three days.

“Sina Weibo calls on the vast number of Internet users to respect the law and regulations, do not spread rumors, do not believe rumors,” said the Internet provider. “On discovering rumors, promptly report them to maintain the healthy Internet environment and good social order.” China has the world’s largest online population, with Internet users numbering half a billion.

Unlike writer Li Delin, the other three weibo users whose accounts were shuttered used assumed names. Long Yi-Tian-945, Guangzhou wu Guancong and Yuangguang De Yuanshi could not be reached by the Associated Press (News - Alert) for comment on this story.

The Chinese government has justified the crackdown and any associated arrests by saying that online commentators “maliciously attacked state leaders” and that the commentators offered “absurd views” about politics.