China's powerful internet regulator has shuttered 17 websites in recent days, including the social media account of liberal economist Mao Yushi.
The websites were shut down because they had been "providing an online news service without a license," state media reported.
"They may also have provided pornographic content, failed to register for an internet content provider license, or "provided fake information during the registration process," the Beijing branch of the powerful Cyberspace Administration said via its official account on the chat app WeChat.
Among the websites shut down was Mao Yushi's Tianze Institute of Economics at unirule.org.cn, and its sister-sites china-review.com and ccppp.org, reported the Global Times newspaper, which has close ties to the ruling Chinese Communist Party.
It said Mao's account on the Twitter-like service Sina Weibo had also been deleted, describing him as "an outspoken economist and free market advocate."
It said Mao had "triggered controversy" for advocating bold reforms and for criticizing the Maoist movement in China.
The shuttering of Mao's account came after he drew a flurry of online criticism from leftist groups in China, who have engaged in a string of public protests targeting prominent liberal intellectuals in recent weeks.
An employee who answered the phone at the Tianze Institute of Economics confirmed the website had been closed down.
"Our website is currently down, and we are now seeking official confirmation of that with the authorities about why this has happened," she said.
"We saw [the statement] but they haven't told us the actual reasons behind it," she said. "We haven't yet received any detailed explanation from them."
Liberal intellectuals targeted
An official who answered the phone at the Beijing Cultural Law Enforcement Agency charged with carrying out Cyberspace Administration directives declined to give details.
"I can't really tell that from here because [a different department] is in charge of carrying out administrative punishments," she said. "If you believe there is a problem with this penalty, then you can report it to our hotline."
Beijing-based sociologist Wang Jiangsong said his WeChat account was also shut down in recent days.
"I think it has to do with the recent linked protests targeted at liberal intellectuals and people arguing for constitutional democracy," Wang said. "I think that these Maoist groups are working together across the entire country."
"[They have targeted people] from Shijiazhuang, Jinan and Beijing, where Tianze and Mao Yushi have long been top of the Maoists' hit-list," he said.
"Using their language, they are seen as top of the list of traitors to the Chinese people who are betraying the country," Wang said.
Online rights activist Wu Bin said China has now entered a post-truth era where fact is exchanged for fiction.
"We are ruled by a dynasty that inverts black and white, and punished people who speak the truth," Wu said. "Online, the punishment is to get shut down, but in real life, the price can be imprisonment."
"Only people who sing the praise of [the regime] can escape punishment ... and are rewarded by the government."
Maoist left activated
U.S.-based academic Wu Zuolai said the authorities are now intensifying their attack on liberal intellectuals, using the Maoist left to help them.
"The first step is to make their websites, their research, disappear, by saying they didn't register properly," he said. "The next step is that, no matter what they do [to fix it], there will still be 'problems,' because this is now a political issue [rather than a bureaucratic one]."
"They are going after dissidents and the pro-democracy faction, one by one," Wu Zuolai said. "Mao Yushi has criticised the Cultural Revolution and Mao Zedong for a long time now, so these people are getting together to denounce him."
"They are saying that Mao Yushi and the Tianze Institute are in receipt of funding from 'hostile forces overseas'," he said.
The website and social media closures come after a chorus of protest from Maoists around the country, amid growing nostalgia and political support for an era of cradle-to-grave socialism, heroic workers, and rousing "red songs."
Chinese authorities have fired three people in recent weeks for being critical of late supreme leader Mao Zedong.
Last week, media and cultural official Zuo Chunhe, of the northern city of Shijiazhuang, was removed from his job as deputy head of the local media regulator for referring to the Chairman as a "devil," state media reported.
The ruling Chinese Communist Party typically retaliates harshly against anyone abusing Mao or his image, as this is held to represent an attack on the founding supreme leader of the People's Republic.
However, it has previously also taken steps to rein in the Maoist left, a growing popular movement in China amid growing social inequality and rampant official corruption.
Political commentators say Maoists are often younger people who have no personal experience of the violence and privations of the Mao era, but who share a deep sense of anger over growing social tensions.
Earlier this month, a flash mob of Maoists descended on a university campus in the eastern province of Shandong, attacking supporters of a university lecturer who retweeted a post satirizing Mao.
The Shandong provincial government then terminated the contract of Deng Xiangchao, a professor at the Shandong Jianzhu University.
Reported by Wong Siu-san and Dai Weisen for RFA's Cantonese Service, and by Yang Fan for the Mandarin Service. Translated and written in English by Luisetta Mudie.