China said Thursday it planned to extend nationwide a requirement for microblog users to register with their real names as part of a sweeping update of rules governing the Internet.

The Ministry of Industry and Information Technology said the revision of rules originally introduced in 2000 aimed to keep pace with change and protect state security, according to a statement posted on its website.

"Many new situations have arisen, (we) are facing new problems," said the ministry, which regulates the industry.

It added the new rules aimed to "promote healthy, orderly development of the Internet, protect state security and public interest".

With more than half a billion Chinese now online, authorities are concerned about the power of the Internet to influence public opinion in a country that maintains tight controls on its traditional media outlets.

Beijing regularly blocks Internet searches under a vast online censorship system known as the Great Firewall of China, but the growing popularity of microblogs similar to Twitter has posed a new challenge.

Under the draft rules, those using Internet chat forums, blogs and microblogs known as "weibo" will have to register with their real names.

Previously, only microblog users in five cities -- the capital Beijing, the commercial hub of Shanghai, the northern port city of Tianjin and the southern cities of Guangzhou and Shenzhen -- were required to do so under a trial that started last December.

In the past, users had been able to set up microblog accounts under assumed names, making it more difficult for authorities to track them down, and allowing them to set up new accounts if existing ones were shut down.

Microblog users criticised the proposed rules, which are open to public consultation for one month.

"More people are speaking the truth on microblogs, so (the government) wants real-name registration to make it easier to arrest them. This is actually a demonstration of their fear," Changsha Ming Ming said.

Another, who gave the name orcl1158, said: "It's stricter, control and regulation are everywhere."

The rules broaden the definition of Internet services, saying online forums, blogs and microblogs must receive government approval, beyond just websites.

The guidelines also require Internet service providers to save keep records of postings and users' information for one year, up from the previous six months, citing the need to crack down on Internet crime.

China's best-known microblogging site, run by Internet giant Sina, last month unveiled new conditions punishing those who post comments deemed offensive, as it comes under government pressure to clamp down on bloggers.