JINAN, CHINA - Sun Wenguang, a retired professor from the Shandong province of northeastern China, who was apparently detained by Chinese authorities during a live-telephone interview with VOA last week, has been moved from a military-run hotel where he was held to an undisclosed location, hotel personnel told Voice of America’s Mandarin Service Sunday morning.

On Thursday, sources told VOA Mandarin that the 84-year-old professor was being detained at Yanzi Mountain Villa at Jinan Military Region, a military-linked hotel and reception center in Jinan, eastern China.

He had been taken away during a live telephone interview on the VOA Mandarin television show Issues & Opinions Wednesday morning as he was criticizing China’s foreign aid and diplomatic strategy in Africa. During the interview, Sun told VOA that authorities were breaking into his house in an attempt to prevent him from speaking out against the government.

After a VOA reporter checked into the hotel in Jinan Saturday, he and an assistant began a surveillance of the professor’s room for signs of movement. The shades remain closed. On Sunday morning, a VOA reporter knocked on the room door. There was no answer.

In interviews with sources at the reception desk on the first floor, the VOA reporter learned that authorities had moved the professor to another location two days earlier.

FILE - Former professor Sun Wenguang speaks in his FILE - Former professor Sun Wenguang speaks in his home in Jinan, east China's Shandong province, Aug. 28, 2013. FILE - Former professor Sun Wenguang speaks in his home in Jinan, east China's Shandong province, Aug. 28, 2013.

?No information on detention

Chinese authorities have disclosed no information about why the professor was detained. VOA tried to reach the Information Department of the Ministry of Foreign Affairs of China for comment, but the mobile phone open to the public was turned off, and the landline was not answered.

The Public Security Department of Shandong University and the Shanda Road Police Station of Jinan’s Public Security Bureau were also contacted. Neither would comment.

The arrest of Sun has come at a sensitive time when the rule of Chinese leader Xi Jinping is being seriously challenged.

Observers say that has led to the security apparatus’ swift action in crushing the country’s rising anti-government sentiments, which they see as a threat to the Communist Party’s regime.

After his “enforced disappearance,” rights activists at home and abroad are demanding that China immediately release Sun for fear he may face physical torture, criminal charges or both.

They also are urging the international society to call for a systemic change of China’s political and legal framework, in which they say the state is continuing to abuse its power and crack down on dissidents.

U.S. Senator Marco Rubio has expressed concern about the professor. “Chinese authorities are increasingly aggressive and brazen in their efforts to stifle free speech and other basic rights. We are deeply concerned for Professor Wenguang Sun’s safety and well-being, and urge his immediate and unconditional release," he said in a statement sent to VOA.

Nodes of independence in China

“It’s absolutely part of the attempts under Xi Jinping to find every little node of independence in society and crush it,” said Michael Caster, co-founder of Safeguard Defenders. Sun’s arrest has to do with “the political situation in mainland China, including the image of Xi Jinping recently also being challenged by [those] both inside and outside [the] establishment.”

“That may also [pose] a security concern” to Chinese authorities, said Richard Tsoi, vice chairman of Hong Kong Alliance.

Caster added that Sun makes an obvious target under China’s intensified crackdown on dissidents since he has had a long track record of being critical of the state and is a signatory of Charter 08, a manifesto drafted by the late Chinese Nobel Laureate Liu Xiaobo to advocate reforms that would result in a separation of powers, a new constitution and legislative democracy in China.

Speaking out

Critics have been emboldened by a recent vaccine scandal in China, a trade spat with the United States, and economic headwinds, and are openly questioning Xi’s sweeping control. This includes Xu Zhangrun, a law professor from Tsinghua University, who has delivered what was believed to be the fiercest denunciation yet of Xi from a Chinese academic.

The New York Times reported Wednesday that Xu “challenged political taboos” at a time when the voice of Chinese intellectuals is dying out.

Xu urged the Chinese government to overturn its condemnation of the pro-democracy Tiananmen protests in 1989, calling on Chinese lawmakers to reverse the vote that abolished a two-term limit on Xi’s presidency.

Many are keeping an eye on how authorities will deal with Xu once he returns to China from Japan or whether he will encourage others to speak out.

Relentless harassment

Before Xu, Sun has long been outspoken, which has made him a target of constant harassment by the communist government.

Earlier this year, Shandong University’s Communist party chapter ruled to cut Sun’s retirement pension by almost half for what it said were his subversive remarks, and it further threatened to eliminate altogether his pension if he continued to talk to foreign media.

Sun had been under intense scrutiny for some time, and security officers had staked out his apartment, keeping a tab on all of his movement.

Rights activists are concerned about what may be coming next for Sun.

“The legal system in China is serving purely to the will of the party, and so if they decide to conjugate some charges against him, then they will. Or they’ll hold him for an indefinite period of time,” Caster said.

He said Sun may share a fate similar to that of his one-time defender and legal counsel, Wang Quanzhang. Wang vanished more than three years ago and has not been heard from since, although he reportedly was seen in the Tianjin No. 1 Detention Center by a former colleague. Wang’s wife has said reports are that her husband is alive in a decent physical and mental state.

Sun also may be forced into making a televised confession. A report from Safeguard Defenders concludes the state has grown heavily reliant on illegal forced confessions by detainees to denounce rights activists and dissidents for both a domestic and international audience.

False charges

In addition, Sun could face charges of colluding with a foreign power, according to Hunan-based rights activist Ou Biaofeng.

“As a minimum, [he will be given] a warning or [put under] house arrest. Or the authorities may make up some false charges against him, for example, collusion with foreign hostile forces,” Ou said, calling authorities in China “barbaric, ridiculous and evil” in suppressing the true voice of its citizens.

International rights groups, including Reporter Without Borders (RSF), have joined hands to throw support behind Sun and demand his immediate release.

“The professor is known for his assertive public interventions against censorship and propaganda. RSF demands his immediate release and stresses that freedom of speech and freedom of the press are explicitly written the Constitution of the People’s Republic of China,” its statement read.

“China may be richer, [but certainly not freer.] The regime has intensified its suppression on rights crusaders and dissidents by having lawyers arrested and using technologies to launch a full-scale surveillance on the public’s freedom of speech online or offline. China has gone overboard,” said Chiu Ee-ling, secretary-general of Taiwan Association for Human Rights.

VOA’s Mandarin Service and Michael Bowman contributed to this report.