(CNN) -- China has around two million people policing public opinion online, according to a state media report that sheds light on the country's secretive internet surveillance operations.
Dubbed "public opinion analysts," they work for the Chinese Communist Party's propaganda department, major Chinese news websites and commercial corporations, according to The Beijing News.
Using keyword searches, their job is to sift the millions of messages being posted on popular social media and microblogging sites such as Sina Weibo, regarded as China's equivalent to Twitter. They then compile reports for decision makers, the report said.
The number of people monitoring internet activity to prevent criticism of the government and social unrest has been a subject of discussion for years, said David Bandurski, editor of the University of Hong Kong's China Media Project.
"Two million sounds like a big number," he said. "But I think it's clear that the government will do what it takes to monitor any potential collective action on social media."
The ranks of online censors outnumber China's active armed forces, which total 1.5 million, according to the Ministry of National Defense.
Bandurski said that the resources China has invested in internet surveillance have increased rapidly since Sina Weibo's emergence in 2010.
It now has 500 million account holders although a recent crackdown on internet rumors has deterred some users.
Posts run a range of topics from celebrity gossip to politically sensitive issues like official corruption.
"China's biggest engineering project is not the Three Gorges dam but public opinion and Weibo has completely changed the game," Bandurski said.
The Beijing News described the work of Tang Xiaotao, who has been employed as a monitor for less than six months by a company that works on government projects.
Using a software application that cost $3 million yuan ($490,000), Tang searches for key words specified by his company's clients, monitors negative opinions and then compiles a report.
The software also tracks how widely a topic is being discussed by counting the number of comments and shares. When the score reaches 40 out of 100, the system will send an alert.
A final decision on what action to take is decided by the clients, which include government officials, Tang told the newspaper.
Online analysts like Tang will be offered specialist training later this month, the newspaper said. The course, run by the People's Daily online operations, covers judging and analyzing online posts and dealing with crisis situations.
Those who pass will get a certificate, formally recognizing them as "public opinion analysts."
Katie Hunt wrote and reported from Hong Kong, CY Xu reported from Beijing