Beijing city authorities on Friday issued new rules requiring microbloggers to register their real names before posting online, as the Chinese government tightens its grip on the Internet.
The city government now requires users of weibos -- the Chinese version of Twitter -- to give their real names to website administrators, its official news portal said.
The new rules will apply to weibo operators based in Beijing, which include Sina -- owner of China's most popular microblogging service which has more than 200 million users.
"Websites with weibo operations must establish and improve a system of content censorship," according to the new rules.
"It is the weibo users' legal duty to use their true ID information to register."
AFP calls to Sina, Netease and Sohu -- two other Beijing-based weibo operators -- went unanswered.
With more than half a billion Chinese now online, authorities in Beijing are concerned about the power of the Internet to influence public opinion in a country that maintains tight controls on its traditional media outlets.
Ordinary Chinese are increasingly using weibos to vent their anger and frustration over official corruption, scandals and disasters.
A weibo user is believed to have broken the news of a deadly high-speed rail crash in China in July that provoked widespread condemnation of the government -- much of it online.
This week, despite attempts to censor the web and a virtual blackout in China's state-run media, weibos have buzzed with news of a protest involving thousands of villagers in the southern province of Guangdong.
Residents in Wukan, which has been under police blockade, have posted information and photos online of their daily rallies to demand justice over land seizures and a local leader's death.
Leading Internet and technology firms have already been pressured to tighten their grip on the web as Chinese leaders try to keep a lid on social unrest in the lead up to a once-in-a-decade leadership transition that begins next year.
Last month the heads of 40 companies, including e-commerce giant Alibaba, search engine Baidu and Sina, vowed to stop the "spread of harmful information" on the web after attending a three-day government workshop.
The seminar was held after propaganda chief Li Changchun, fifth in the Communist Party hierarchy, met the heads of China's main search engine Baidu in September.
That same month, the head of Sina said the web giant had set up "rumour-curbing teams", apparently in response to government pressure.
The Internet has posed a huge challenge to government attempts to block content it deems politically sensitive through a censorship system known as the "Great Firewall".
The number of weibo users has more than trebled since the end of 2010, according to government data, and the speed with which they have taken off has made it impossible for censors to keep up.
Explore further: China's Sina to launch English microblogging site