Chinese authorities have stepped up a nationwide "stability maintenance" operation ahead of the 28th anniversary of the 1989 military crackdown on the Tiananmen Square democracy movement.



As outspoken Beijing University law professor and social media star He Weifang said he would quit posting following repeated shutdowns of his accounts, many other outspoken critics of the ruling Chinese Communist Party are being placed under house arrest or close police surveillance ahead of the sensitive anniversary, activists said.



"Every year, in the run-up to June 4, rights activists are all placed under house arrest," Beijing-based activist Hu Jia told RFA. "Professor He won't be, although he may receive some kind of warning."



He said the authorities are also stepping up controls of dissidents ahead of a major political meeting later in the year, the national Party Congress.



"Also, this year, we've got the 19th Party Congress coming up, so that's what most of the stability maintenance will be focused on," he said, adding that the silencing of He Weifang is an indicator of how far the administration of President Xi Jinping is prepared to go to create an impression of public harmony in the coming months.



Hu said He Weifang's comments aren't even particularly sensitive or outspoken.



"He never says anything that he wouldn't say in his own classroom, or speaking to his students," Hu said. "The party only started to regard him as a threat when he started to wield some influence [via his social media following]."



He Weifang told The Associated Press on Friday: "I feel utterly helpless. It’s as if I’m not allowed to make a single sound."



Beijing-based rights lawyer Li Jinglin said he was completely unsurprised by He's decision.



"All of the big tweeters in China have been shut down," Li said. "They are actually saving face by allowing him to decide to retire of his own accord."



"The Communist Party has no reason to allow different opinions."



Tightening controls



Activists across China have reported tightening police controls and surveillance in recent days.



Jiangsu-based activist Zhang Kun is currently under house arrest as part of the same operation, Hubei-based fellow activist Wu Lijuan said.



"It's all to do with the stability maintenance operation ahead of June 4," Wu said. "Zhang Kun often tweets various comments and thoughts of his online relating to democracy, and the sensitive date has nearly arrived."



"I think the government just wants him to take a break."



And Guangzhou-based activist Huang Simin said she was recently contacted by police, who warned her and her husband and writer Li Xuewen not to leave town ahead of the anniversary, after which the lock on their apartment door was blocked up with glue by unknown individuals while they were outside it.



So the couple had climbed back in through a window to pick up their ID, before leaving town anyway, she said.



"There is no real reason for them to put such obstacles and difficulties in our path," Huang said. "The authorities are acting illegally by doing this."



"I'm busy with something else now," she said. "I'll worry about that after I get back to Guangzhou."



And in the eastern province of Shandong, activists said they had managed to hold a public meeting to commemorate those who died in the bloodshed that ended weeks of pro-democracy demonstrations in the summer of 1989.



Retired Shandong University professor Sun Wenguang said the meeting took place on May 24, after which the number of state security police watching the door of his apartment rose.



The activists had originally planned to go to Thousand Buddha Mountain in Jinan and meet, but the police discovered the plan while they were en route, so they held the ceremony at Sun's home instead, he told RFA on Tuesday.



"A lot of my friends managed to evade police interference and [came here] to commemorate June 4, 1989," Sun said.



"Around a dozen people were heading towards Thousand Buddha Mountain ... but before they had gotten to the top, around a dozen police arrived in three cars and followed and surrounded them," he said.



The activists had been forced to call off their plan, Sun said.



"There are now more than 20 police outside our home, so I made a speech outside the building for about 20 minutes," he said. "I was talking mostly about the meaning of June 4 in Chinese history, that the Chinese Communist Party killed students with gunfire, and we want the leaders of the Communist Party at that time to be held responsible, including Deng Xiaoping."



28th anniversary



In the 28 years since the PLA crackdown, the Tiananmen Mothers victims' group have called repeatedly for a public inquiry into the massacre and the pursuit of those responsible. They also want compensation, and a detailed account of who died, how and where.



The government styled the student-led democracy protests, sparked in April 1989 by the death of much-loved liberal premier Hu Yaobang, a "counterrevolutionary rebellion."



Public memorials and discussions of the events of June 1989 are banned, with activists who seek to commemorate the bloodshed often detained and veteran dissidents placed under police surveillance or detention during each anniversary.



Reported by Qiao Long and Gao Shan for RFA's Mandarin Service, and by Wong Lok-to for the Cantonese Service. Translated and edited by Luisetta Mudie.