The ruling Chinese Communist Party has published a warning to its officials using the popular chat app WeChat, banning them from making "off message" comments on social media.
"WeChat friends circles are not a private domain, but a public place," according to a list of seven "dos and don'ts" issued by state news agency Xinhua's opinion column.
It said newly revised Communist Party rules for cadres now list "use of information networks to make rash comments on central government policy" as a disciplinary violation.
According to Xinhua, that could include using "information networks, radio, television, newspapers, books, lectures, forums, reports, seminars and other means to make off message comments about central government policy and undermine party unity."
Cadres whose WeChat networks contain "negative energy" should take time to persuade and educate their social media friends, and to "make the facts clear," the article said.
It said cadres are also banned from posting about government business to either official and personal social media accounts without authorization.
"Confidential information about government or [state] employers mustn't be posted, even in private one-to-one messages," it said, saying leaks were "likely."
Further limits to expression
The guide comes as China continues to tighten its control over what its 730 million internet users can see online, with new restrictions on virtual private networks (VPN), which are widely used to access restricted content outside the Great Firewall.
But Zhejiang rights activist Wu Bin said the guide's purpose is to ratchet up controls over what government officials may say in public, too.
"I'm not surprised by this, because it's all about [further] limiting freedom of expression, and taking away people's right to speak out," Wu said.
"The controls over [Twitter-like] Weibo services and WeChat are getting tighter and tight, and I think it's going to get even worse in future," he said.
Anhui-based activist and former state prosecutor Shen Liangqing said the ruling party has never felt comfortable with any sort of freedom of expression.
"Now we are in the internet age, rapid changes are taking place, such as chat apps, which have the ability to set up fairly small circles of communication," Shen said.
But he said WeChat, which is owned by Tencent, is still a commercial entity.
"If this was a normal country we wouldn't have all these controls on free speech," Shen said.
Liaoning Normal University professor Mu Ran said via social media that social media is fast becoming an echo chamber for party officials to support government policy,.
"There's no trace of public opinion left in this at all," Mu wrote.
The new code of conduct banning "off-message" statements was likely approved by the plenary session of the 18th Party Congress last October, which was held behind closed doors, political observers said.
That meeting also formally endorsed President Xi Jinping as a "core" leader of the ruling party at the current plenum, potentially putting him on a par with former paramount leaders Mao Zedong and Deng Xiaoping, whose authority must never be challenged.
China's Cyberspace Administration last week shut down the WeChat account of prominent liberal economist Mao Yushi, without giving details.
The agency has also set out plans to defend the country's "national sovereignty" in the part of cyberspace behind the Great Firewall, a complex system of blocks, filters, and human censorship.
Reported by Xin Lin for RFA's Mandarin Service. Translated and edited by Luisetta Mudie.