HUNDREDS of millions of Chinese began posting on social networks, including Sina Weibo, using their real names, after the government brought in new rules to make it easier to track people across the internet.
In the past three years, microblogs such as Sina's Weibo (Way-Bwor) have become hugely popular sources of information, to a large extent displacing China's state-owned television channels and newspapers.
Sina's Weibo now has more than 250 million users, a near 300 per cent rise in the last year, posting a largely unfettered stream of news, gossip, entertainment, scandal and opinion in real time.
But the phenomenon has unnerved some in the Communist party.
Microblogs are trickier to censor because of the rapid stream of information flowing through them, and there is also the potential for rumours to spread rapidly, and potentially dangerously.
Microblogging, said Wang Chen, a minister at the State Council Information Office, can "have a big influence, cover a wide population, and mobilise people".
Earlier this month, a false rumour that Kim Jong-un, the new North Korean leader, had been assassinated in Beijing swept through the internet, much to the embarrassment of the Chinese leadership.
In response, the new rules force users to register their identity card numbers or mobile telephone numbers with Sina and the other microblog operators before they can start posting onto the platform.
In response, Sina said that some 40 per cent of its users had already failed the verification process, and that the rules would affect its profits for the year.
"We estimate that by the deadline, the majority of our users, about 60 per cent of them would have successfully registered their identities," said a Sina spokesman.
According to the rules, anyone who is not registered will continue to be able to read Weibo, but not post onto it.
A quick test yesterday revealed however, that it was still possible to post without leaving a name.
A second regulation requires Sina to review the posts of users who have more than 100,000 followers, deleting any posts that are harmful to "national interests" within five minutes.
Campaigners for freedom of information said that the new rules would deter many people from exposing, or passing on, sensitive information in case they suffer repercussions. It was not clear how closely Sina would be required to share its registration details with the government.
However, one senior Chinese official involved in monitoring the internet, who ironically asked not to be named, said the authorities were already capable of tracing the sources of any sensitive information.
"Having people register with their real names will not hamper Weibo.
"This rule asks everyone to take responsibility for their speech and actions. There is no such thing as absolute freedom," he said.
"The people who have large followings on Weibo already use their real names. Celebrities have all been verified, for example. And it will not stop whistle-blowers: in fact, everyone will be able to see, transparently, how they are treated by the authorities.
"As for using the rules to catch people. Well, they do not need your real name information to find you. The authorities can already find out when and where you logged in. They can find out exactly which computer was used. They do not need your name to catch you."
It is unclear how the new rules will apply to the eight million or so users who post on Weibo from overseas, including the likes of Bill Gates, Tom Cruise and Emma Watson, the actress. Without an identity card number, they may not be able to complete the registration process.
Meanwhile, some analysts suggested that although the number of people using Sina's Weibo is likely to drop, advertising revenues could rise, since real name registration will weed out spam accounts and allow advertisers to identify their target audience.