Chinese property tycoon Ren Zhiqiang has had his microblogging accounts shut down by the Beijing authorities after he criticised President Xi Jinping.
The Cyberspace Administration of China said Ren had published "illegal messages that had a bad impact".
"The cyberspace is not outside the laws, nobody is allowed to spread illegal information using the internet," Jiang Jun, spokesman for the Office of the Central Leading Group for Cyberspace Affairs, was quoted as saying in a statement.
Beijing was angered by a post Ren had written, saying that state media were funded by taxpayers and should serve them, not the Communist Party.
President Xi urged state media early this month to follow party lines in their reporting.
China has been criticised for its strict internet regulations, including blocking major sites and censoring posts. But Xi has argued that countries had the right to choose how to develop and regulate the internet.
Ren is a retired top executive from a state-controlled property developer who has more than 30m online followers.
According to a commentary posted on 22 February on china.qianlong.com, a website run by the Beijing municipal government, Ren, a communist party member, was accused of making remarks against the state media and the party.
"Who gave Ren the courage to be anti-party?" was the title of the commentary, which also called him "cannon Ren who's only a proxy for the capitalists".