Chinese online activists have complained in recent days of a huge upsurge in the volume of microblog posts from netizens they say are in the pay of the government.
Prominent artist and social critic Ai Weiwei launched a campaign this week to find out the identities of those who repeat the official line of the ruling Communist Party online.
Ai said he was currently trying to interview the government-backed commentators, known on China's Internet as members of the "fifty-cent party," about their shadowy role in the formation of public opinion. Fifty cents refers to the alleged paltry sum the Internet commentators receive per post.
Netizens have been saying for years that the government pays people to post comments online and sway public opinion in its favor, with a noticeable increase in such comments in recent weeks.
"I think they have probably been collectively mobilized [to propagate the government's point of view] in a united manner on Twitter," said Fujian-based blogger and online activist Peter Guo.
He said the posts are characterized by a lack of individual thought and action, as well as 24-hour activity.
"They are acting in a professional capacity," Guo said. "They aren't expressing their own true opinions on Twitter."
Google searches
Netizens said the undercover Internet commentators continue to send out updates around the clock, and that their microblog posts now feature prominently in any Google searches.
"The recent surge of ... [their] activity on Twitter I think is linked to the Jasmine revolution," said Guo, referring to recent calls online for "Jasmine" protests inspired by recent popular uprisings in the Middle East.
"In a normal society you should be able to hear all manner of opinion," Ai said. "Their actions are not normal, because they're organized."
"They take on these concepts because they're doing their job, and I think that runs counter to the spirit of free speech."
"I want them to tell us who they really are, and why they choose to do work like this. I want to interview them and get them to speak more clearly."
Elusive
However, the undercover authors have proved elusive so far.
Netizen Elaoda said there was no point in drawing up a blacklist of suspicious accounts, because the users would simply re-register in a different account name.
The move comes after netizens found a number of pro-government updates on popular microblogging services purportedly in the name of key pro-democracy activists.
Among the accounts imitated was that of exiled 1989 student leader Wang Dan, whose Twitter account @wangdan1989 was impersonated as @wangdanl989, they said.
The government meanwhile hit out at what it called "Internet mercenaries," although it did not specify the sort of opinions which were being targeted.
"China should be cautious about 'Internet mercenaries,' a group of people posting comments online to manipulate public opinion," Zhao Qizheng, spokesman for the Chinese People's Political Consultative Conference, told reporters on Wednesday.
"The influence of public opinion via the Internet is getting stronger as more and more people use the channel to exchange views and participate in political issues," Zhao said.
Public opinion
China had 457 million Internet users by the end of last year, and the government recently identified microblogging services like Twitter and Sina Weibo as powerful drivers of public opinion online.
"There has emerged a group of people called Internet mercenaries," Zhao was quoted as saying by the official Xinhua news agency.
"Some of them, backed by institutions for certain purposes, disguise themselves as ordinary netizens and post comments in order to affect and divert public opinion, or even disturb government policy-making," he said.
Experts say Chinese enterprises also hire netizens to spin a particular public relations angle on popular websites, or to turn the tide of public opinion in their favor in the event of a dispute or scandal.
Top Internet analyst Zhang Zhengjun said the key to greater clarity online is more freedom of information, not less.
"The channels of information shouldn't be muddied," he said. "That way, it's easy to get a rash of negative posts [in reaction]."
"If there is greater transparency, then even if people start to spread rumors on the Internet, no one will believe them," Zhang said.
National People's Congress
Delegates to the forthcoming National People's Congress (NPC) and Chinese People's Political Consultative Conference (CPPCC) this week have taken to microblogging to connect with ordinary people ahead of the annual parliamentary sessions.
But the move has been criticized by analysts as yet another online public relations stunt.
"It's all really about a public image and creating some hype ahead of the parliamentary sessions," said Li Xiaobing, director of the Western Pacific Institute at the University of Central Oklahoma.
"It really serves a propaganda purpose."
U.S.-based political activist Liu Nianchun agreed.
"The limits of the microblogging exchange are all predetermined ... None of the ordinary people are going to say what they are really thinking," he said.
"Especially now as there is compulsory real-name registration for micro-blogging services in China, which will add to the apprehension of ordinary people."
Reported by Wen Jian, Yang Jiadai and Xin Yu for RFA's Mandarin service. Translated and written in English by Luisetta Mudie.