Image caption Sina Weibo, launched in 2010, has more than 500 million registered users with 100 million messages posted daily

More than two million people in China are employed by the government to monitor web activity, state media say, providing a rare glimpse into how the state tries to control the internet.

The Beijing News says the monitors, described as internet opinion analysts, are on state and commercial payrolls.

China's hundreds of millions of web users increasingly use microblogs to criticise the state or vent anger.

Recent research suggested Chinese censors actively target social media.

The report by the Beijing News said that these monitors were not required to delete postings.

Analysis China's internet is one of the most controlled and censored in the world. Websites deemed to be subversive are blocked. Politically sensitive postings are routinely deleted . Even the name of the former Prime Minister Wen Jiabao was censored when rumours were circulating on the internet that his family had amassed a fortune while he was in power. But with the rapid growth of internet users, the ruling Communist Party has found itself fighting an uphill battle. The Beijing News, while reporting the story of microblog monitors, has admitted that it is impossible for the government to delete all "undesirable" postings. The more postings deleted, the more they appear, it says. China seldom reveals details about how it monitors and controls the internet. The government even does not acknowledge that it blocks web sites. But the report does offer a rare glimpse into this opaque world.

They are "strictly to gather and analyse public opinions on microblog sites and compile reports for decision-makers", it said. It also added details about how some of these monitors work.

Tang Xiaotao has been working as a monitor for less than six months, the report says, without revealing where he works.

"He sits in front of a PC every day, and opening up an application, he types in key words which are specified by clients.

"He then monitors negative opinions related to the clients, and gathers (them) and compile reports and send them to the clients," it says.

The reports says the software used in the office is even more advanced and supported by thousands of servers. It also monitors websites outside China.

China rarely reveals any details concerning the scale and sophistication of its internet police force.

It is believed that the two million internet monitors are part of a huge army which the government relies on to control the internet.

The government is also to organise training classes for them for the first time from 14 to 18 October, the paper says.

But it is not clear whether the training will be for existing monitors or for new recruits.

The training will have eight modules, and teach participants how to analyse and judge online postings and deal with crisis situations, it says.

The most popular microblogging site Sina Weibo, launched in 2010, now has more than 500 million registered users with 100 million messages posted daily.

Topics cover a wide range - from personal hobbies, health to celebrity gossip and food safety but they talso include politically sensitive issues like official corruption.

Postings deemed to be politically incorrect are routinely deleted.