A senior Chinese propaganda official has said real-name registration for the nation\'s hugely popular microblogs will be expanded, as authorities tighten their grip on the web amid fear of unrest. Beijing, Shanghai and the southern province of Guangdong have recently ordered new users of weibos -- microblogs similar to Twitter -- to register using their real names, making it easier for authorities to track them. \"This started at the end of last year. At first it applies to new users only, and it will then be expanded to existing users,\" said Wang Chen, the minister in charge of the press office of the State Council -- China\'s cabinet. He told reporters weibos had exploded in popularity, with hundreds of millions of loyal users who wrote around 150 million postings every day. \"Weibo is a new Internet application. It\'s speedy, influential, and has a wide reach and strong potential for mass mobilisation,\" he said on Wednesday. With more than half a billion Chinese now online, authorities are concerned about the power and influence of the Internet to spark unrest in a country that maintains tight controls on traditional media. The government exercises tight censorship over the web in a system dubbed the \"Great Firewall of China\", and is particularly nervous as the country will undergo a major leadership transition towards the end of the year. But despite the controls, people are still using weibos to vent their anger and frustration over official corruption, scandals and disasters by re-posting information and images as fast as the authorities can take them down. Residents in Guangdong protesting against land seizures and a power plant last month posted photos and reports of their demonstrations on weibos, defying official efforts to block news of the incidents. At least one of the protests ended with an apparent victory for local residents.