Authorities in the southwestern province of Sichuan have detained a former professor at a ruling Chinese Communist Party school after he called for President Xi Jinping's replacement.
Zi Su was taken away from his home in Sichuan's provincial capital Chengdu on April 28 after he posted an open letter online calling on Xi to step down as head of the party in favor of Hu Deping, son of late ousted premier Hu Yaobang, whose death in 1989 sparked the Tiananmen Square democracy movement.
"Xi Jinping was elected general secretary ... in 2012 and has served for five years," Zi's letter said. "His achievements ... have been to punish a number of corrupt officials, but his faults have been to imitate [late supreme leader] Mao Zedong with a personality cult around him and a focus on centralization of power."
"He serves as the head of a dozen groups or committees, which goes against the democratic constitutional orientation of reforms to the political system, and he has launched an unbridled attack on human rights lawyers and democracy activists, as well as increasingly clamped down on online free speech," the letter, posted on the Weiquanwang rights website, said.
"His anti-corruption campaign has been waged under a one-party dictatorship ... and he has made use of the Central Commission for Discipline Inspection to ... carry out selective anti-corruption work," it said.
"But his biggest mistake of all has been to institute the "seven taboos," comprehensively restoring the ideology of the Mao era, which was openly opposed by Deng Xiaoping, Hu Yaobang, Zhao Ziyang and other party leaders who advocated reform," Zi wrote.
"Many people inside and outside the party believe that Xi Jinping is unsuitable to continue in the post of general secretary," he said. "I suggest ... that Hu Deping takes over. Those who agree can add their signatures to my proposal."
Within hours of posting the letter, Zi had been taken away, posting a photo on Sunday to WeChat to let people know he was safe, sources close to him told RFA.
"The first we heard from him was 24 hours after he disappeared, when he posted a photo to WeChat showing himself sitting in a teahouse," an associate surname Liu said on Tuesday. "He wrote that he was having a good think somewhere about a number of matters, but it was quite vague."
"He just wanted to let people know he is OK."
Liu said Zi's family have yet to receive any official notification regarding his 'disappearance.'
"Some people are staying in his WeChat group [as a way of maintaining communication], while others have withdrawn out of concern for their own safety," he said. "I hope they release him soon."
Zhu Delong, a friend of Zi's, said he doesn't believe his friend is at liberty, regardless of the photo.
"All my communications are being monitored right now," Zhu told RFA. "So I can't speak freely, I can't really help you, because I'm being monitored as well."
"My phone is being monitored and I have been banned from ever using WeChat again," he said. "I have been shut down for good."
Zhu said he believes Zi's detention has to do with the open letter.
"That thing he sent out was pretty sensitive," Zhu said. "If he has been detained, then they should notify his family ... so you'll have to ask them."
Asked if he fears for his own safety, Zhu said: "Of course I'm worried, but what can I do about it? I'm in my sixties now, anyway."
A duty officer who answered the phone at the Chengdu municipal branch of the state security police, who detained Zi briefly last October on suspicion of "incitement to subvert state power," declined to comment.
"I don't really know about this, but if he has been detained by us, they will inform the family," the officer said. "You can ask them. If there's no notification, there's no notification."
Calls to the Chengdu municipal police department rang unanswered during office hours on Tuesday.
Zi was detained on Oct. 27 and held briefly in the Sichuan No. 2 Detention Center, before being released, suggesting that he may have remained on police bail.
The outspoken professor had previously told RFA as the party celebrated its 95th birthday on July 1, 2016, that Xi was using "controls and political struggle of the kind used by Mao Zedong."
Reported by Wong Lok-to for RFA's Cantonese Service, and by Xin Lin for the Mandarin Service. Translated and edited by Luisetta Mudie.