Beijing's vow to strengthen Internet administration and promote content acceptable to the ruling party appeared in the communique of a recent party leadership conclave published in the official People's Daily on Wednesday.
Communiques from the Communist Party's Central Committee, which held its annual meeting this month, set the broad agenda for policy-makers.
This one made clear that party leaders are looking for ways to better control, but not snuff out, the microblog services that have become popular channels for spreading news and opinion that can unsettle the government.
"Strengthen guidance and administration of social Internet services and instant communications tools, and regulate the orderly dissemination of information," said the communique, which made no reference to microblogs as such.
"Apply the law to sternly punish the dissemination of harmful information," added the document. It did not give details of what form firmer regulation may take.
The announcement from the Party meeting builds on a stream of warnings in state media that has exposed how nervous Beijing is about the booming microblogs, called "weibo" in Chinese, and their potential to tear at the seams of censorship and controls.
But analysts said the business impact was likely to be muted, because investors are used to growing official scrutiny of Chinese Internet companies and the government is unlikely to shut down what has become an important valve for monitoring and easing social pressures.
"There will be tighter censorship, but the impact on the platforms won't be much. I don't think the government will implement nation-wide regulations because that will be negative for the government and the companies," said Hong Kong-based CLSA analyst Elinor Leung.
Chinese microblogs, especially Sina Corp's dominant service, carry plenty of gossip and harmless fare.
But they also offer raucous forums for lambasting officials and reporting unrest or official abuses. It is their potential to stoke popular discontent that most worries Beijing.
Microblogs allow users to issue bursts of opinion -- a maximum of 140 Chinese characters -- that can cascade through chains of followers who instantly receive messages, challenging censors who have a hard time monitoring the tens of millions of messages sent every day. Inventive users adopt alternative words to get around censorship filters.
A bullet train crash in Wenzhou this July was a watershed moment for Sina's "Weibo" microblog service as thousands of users expressed anger at the official response and pulled apart official accounts of the crash and rescue response.
More recently, an uproar spread on Sina's Weibo when a two-year old girl who was run over by two trucks and then ignored by passerbys as she lay bleeding. She later died.
The number of Chinese users registered on domestic microblog sites reached 195 million by the end of June, a more than threefold increase on the number at the end of 2010, according to the China Internet Network Information Center.
A top Chinese Internet regulator this month also called for stricter policing of microblogs while encouraging officials to use them to engage with citizens, indicating that Beijing was looking to better control such services, but not shut them down.
Sina and other Chinese microblog operators already deploy technicians and software to monitor content and block and remove comment deemed unacceptable, especially about protests, official scandals and party leaders.
Excessive self-censorship on the microblog platforms risks alienating off users by making them bland, analysts said.
"The more important risk we see for Sina Weibo and other Weibos is that they self-regulate out of business (interests)...and that they self-neuter and that makes the platform so boring no one wants to use it," said Michael Clendenin, the managing director of RedTech Advisors. --Reuters