Authorities in the southwestern Chinese province of Sichuan are believed to be holding dissident and 1989 pro-democracy movement veteran Chen Yunfei for marking the anniversary of a massacre of civilians in Beijing on June 4, 1989.
Friends of Chen's said he has been incommunicado a couple of days ahead of Thursday's anniversary of the bloodshed that ensued when the ruling Chinese Communist Party leadership ordered the People's Liberation Army (PLA) to clear downtown Beijing of protesters using machine guns and tanks.
His apparent detention comes after some 200 rights activists launched an online event to mark the 31st anniversary of the massacre on Sunday.
The government bans public memorials marking the event, and has continued to ignore growing calls in China and from overseas for a reappraisal of the 1989 student protests, which it once styled a "counterrevolutionary rebellion."
Chen had commented, as part of the event: "We have seen wave upon wave of civil unrest and grievances in Hong Kong, from the  Article 23 protests to the anti-extradition movement and the opposition to the national security law."
"[We have also seen] the Sino-U.S. trade war and the coronavirus that spread from Wuhan across the whole country and then throughout the whole world," he wrote.
"These things show us that the Chinese government hasn't found the root of popular malaise, and also that the things we were fighting for in the 1989 protest movement were the right things," Chen said. "There is no reason why we shouldn't publicize and commemorate June 4 in any number of ways."
Chen has been incommunicado, and no longer at his apartment in Sichuan's provincial capital Chengdu, since posting the comments.
Chen's friend Li Jinfang said he is worried about him.
"A friend told me that they were unable to reach him on the night of May 31," Li said. "This news made me very anxious, and I tried calling him again."
"His phone was still on at that point, but nobody picked up."
Li added: "I think he has been taken away because this is a [politically] sensitive time of year; it's definitely related to [June 4]."
Chen had previously been sentenced to four years' imprisonment over his commemoration of the Tiananmen massacre by visiting the grave of a 1989 student protester in 2015.
Independent journalist Gao Yu said she had been planning to take part in the online commemoration, but had been pressured by the authorities not to.
"[Security] this year is particularly tight, partly due to the parliamentary sessions, and partly June 4, which have come at the same time [owing to the coronavirus pandemic]," she said.
"I was told that I had to come on a tour of Beijing with them, and that there would be police at every intersection," she said.
"The national security law in Hong Kong and the U.S. sanctions mean that things are no less tense than they were last year, for the 30th anniversary," Gao said.
Beijing rights activist Hu Jia said he is also being placed under house arrest at an unknown location ahead of Thursday's anniversary.
"I have to leave my home tomorrow morning [with the police], and I don't know where they are taking me," Hu said. "Not necessarily out of town, you understand, but maybe a suburb of Beijing."
Hu said he always fasts from 8.00 p.m. on June 3 to 8.00 p.m. on June 4 every year, out of respect for the victims of the massacre.
"If I am at home, I will light a candle, and think of the people who died," he said.
Activist Chen Siming, who was detained police in Hunan's Zhuzhou city in 2018 for taking photos in a park with a tank in the background on June 4, is also under close surveillance, and has been forced to take a "vacation" with police to the eastern province Jiangxi.
Chen nonetheless managed to take a June 4 selfie and upload it to the social media platform WeChat while the officers guarding him were distracted.
Zhang Xianling, whose teenage son died in the Tiananmen massacre, said the families of those who died may not be able to go to the cemetery together to pay their respects on Thursday.
But she said they may be allowed to go in separate groups, citing social distancing restrictions under the coronavirus pandemic.
"The pandemic may be an excuse, but it's kind of a legitimate one," Zhang said. "We can go by ourselves, and we don't need [the police] to provide transportation."
Reported by Gao Feng for RFA's Mandarin and Cantonese Services. Translated and edited by Luisetta Mudie.
Copyright © 1998-2018, RFA. Published with the permission of Radio Free Asia, 2025 M St. NW, Suite 300, Washington DC 20036