China's micro blogging platform Sina Weibo, a phenomena whose echo chamber frequently targets foreign companies, often in campaigns and memes initiated by shady and commercially self-interested bloggers (sometimes with opaque support of the State), is in a funk.

Weibo has fallen foul of the Chinese Communist Party and the instruments of government it controls. 

The company's subscriber numbers are falling, and its dominant position in China's social media melee is under challenge by platforms such as WeChat, which has grown quickly to host 300 million subscribers to Weibo's roughly 500 million.

A privately owned corporation with 54 million active users daily, Weibo - the equivalent of Twitter - has strayed to close to to giving its bloggers with large social media following a voice in an increasingly controlled and censored social media universe.

Until recently, the government apparatus has been silent when Weibo users crucified foreign brands and corporations for sometimes confected, and less often real, transgressions of China's complex and opaque regulatory regime.

In 2012, former Premier Wen Jiabao exhorted China's citizens to use social media platforms to keep corporations responsible and honest, which was seen by some as an attempt to divert social media attention from the government and its performance. 

Local companies competing with multinational entities are very infrequently the focus of Weibo comment and dialogue about product or service quality, or regulatory transgressions.

Until earlier this year the government lurked in Weibo's online shadows as censor of comments and memes it considered unhelpful to its interests. But it has moved to a new phase of censorship. The national government's 'Forum on Social Responsibility of Internet Celebrities' has had enough, and has warned and even arrested some of Weibo's most popular and influential bloggers.  

"The purification of the online environment" is how a senior official quoted in the foreign media described the arrest and public denunciation of a popular Chinese- American venture capitalist Charles Xu, who had used Weibo to question the way in which poor Chinese from rural areas were being treated as workers in the cities. Mr Xu disappeared from Weibo and from his home. He reappeared recently on Chinese television news in shackles, charged with 'soliciting' a sex worker, though the only comments by him about his arrest (broadcast on national television) decried his own failure to understand that freedom of speech cannot override the law. 

Since the beginning of 2013, a number of Weibo'a bloggers with the largest following have been shut down, or have disappeared from the conversation if they strayed into raising issues that may reflect poorly on the government, including questioning China's food and air quality standards.

And in late September 2013, amid outrage internationally and internal dissent in China, a 16 year-old boy was arrestedby local authorities for 'rumour-mongering' via Weibo, after he raised questions about the murder of a karaoke club manager in mysterious circumstances in China's north west Gansu Province.

The boy has since been released, despite his reported confession to the crime of 'rumour-mongering' carrying a three-year gaol term. Soon after his release, he used his Weibo account to thank supporters across China (who railed publicly against his arrest and the crack-down on free speech online). Within an hour, his Weibo account disappeared.

Whether or not China's authorities can restrict Weibo posts and conversations to the real or confected misdeeds of foreign brands and companies, and the banalities of daily life, is as contentious as the future of Weibo itself as China's premier social media platform.

More certain, however, is that the Forum on Social Responsibility of Internet Celebrities, as well as other authorities, are serious about "purification" of China's online commentary.