China's state security police have formally arrested dissident Xu Zhiyong for subversion after he called publicly on President Xi Jinping to resign.

Xu, who has already served jail time for his spearheading of the New Citizens' Movement anti-corruption campaign, penned an open letter to Xi while in hiding following a gathering of pro-democracy activists and lawyers in December 2019, calling on him to step down.

He is currently being held incommunicado in "residential surveillance at a designated location" (RSDL) pending the completion of the investigation.

RSDL allows police to hold anyone they say is suspected of crimes linked to national security without contact with family or a lawyer for up to six months.

Xu is currently being investigated for "incitement to subvert state power by a team of state security police based in the eastern province of Shandong that has been pursuing a number of participants in December's gathering in the southeastern port city of Xiamen.

Human rights lawyer Ding Jiaxi is a co-defendant in the same case, RFA has learned.

Xu Zhiyong's sister was notified by the Shandong police on June 20 that Xu had been formally arrested, but his location remains unknown.

Xu Zhiyong's friend and independent documentary director Hua Ze meanwhile said the "meeting" was merely a gathering of friends.

"The police are treating this as if it is a big case, and claiming that there is an organization at work, but actually it was just a group of friends getting together," Hua said.

"They were just talking about how to help some of the current [detained activists'] cases, and follow up on them," she said.

Liu Jiacai, a rights activist from the Yangtze river city of Yichang who is often targeted by state security police, said he is currently safe at home after being taken out of town for the sensitive June 4 anniversary of the Tiananmen massacre.

"Xu had written a lot of articles since the start of the coronavirus pandemic," Liu said. "Anyone who attended the Xiamen gathering is now being suppressed by the authorities, and many people no longer dare to speak out."

"But Xu kept insisting on speaking up ... I feel bad that he was detained, as his friend and fellow activist," he said.

Liu said the Xiamen gathering was a meeting of like-minded friends who discussed social phenomena and China's future.

"We did not violate the Constitution or the current laws of China, but the authorities have persecuted us anyway," he said.

Fears over possible torture

Ding Jiaxi�s wife Luo Shengchun says she fears her husband, who is also being held under RDSL detention, may be being tortured.

"My sense is that he is being subjected to torture," Luo told RFA. "The people who came out [after being interrogated as part of the investigation] wouldn't talk about it; they had been silenced."

"This is clearly about framing Ding Jiaxi; they haven't been able to find any evidence of criminal behavior, but they will keep on finding excuses to keep him in detention because he refuses to plead guilty," she said.

Luo said she is certain that Ding Jiaxi will never cave in to police pressure to "confess" to the charges against him.

"This is a red line for him, because he is innocent," Luo said. "They came before to try to persuade him, and he told them they should be trying to persuade the bad guys not to do bad things, not trying to persuade the good guys not to do good things."

Writers' group PEN America, which recently honored Xu with the PEN/Barbey Freedom to Write Award, on Monday condemned Xu's formal arrest.

"Xu Zhiyong is under arrest for criticizing the government, plain and simple," PEN CEO Suzanne Nossel said in a statement. "By proceeding with these meritless charges of �subversion,� the government is using the law as a tool to legitimize its suppression of dissidents. But criticisms are not crimes, no matter how much Beijing insists otherwise."

She added: "We have zero confidence that Xu will receive a fair trial. We insist that the government drop these absurd and abusive criminal charges against him, and acknowledge his right to express his ideas and opinions without fear of a jail cell."

Critical flaws in proposed resolution

The news of Xu's formal arrest emerged as the United Nations Human Rights Council (HRC) held a brief debate in Geneva on June 22 over a draft resolution presented by China, raising "serious concerns" about the future of the Human Rights Council and, more broadly, the multilateral UN human rights system, rights groups said.

The overseas-based Chinese Human Rights Defenders (CHRD) network said there were "critical flaws" in the resolution, which would limit the council's ability to hold member states to account for human rights violations.

"The draft resolution, once put into effect, would codify language directly taken from Chinese Communist Party propaganda � namely, China�s promotion for a �shared community of future� modeled on its authoritarian governance at home � and its attempt to silence criticisms of rights abuses in the Human Rights Council platforms," the group said in a statement.

Xu had also penned a New Year's message to China's citizens in 2020, calling on them to think about whether they want to carry on with an authoritarian government or movement towards democratic constitutionalism, an idea that President Xi has said has no place in his vision for China.

Dozens of people linked in some way to the New Citizens' Movement group have been detained and jailed in recent years.

Xu was handed a four-year jail term in January 2014 on public order charges after staging a street protest calling for greater transparency from the country's richest and most powerful people.

Ding Jiaxi, who has previously served jail time for calling on top officials of the ruling Chinese Communist Party to reveal details of their wealth, was stopped by police at Beijing International Airport in May 2018, as he tried to board a plane to visit his wife and daughter in the U.S.

He was also among more than 300 rights attorneys, law firm staff, and associated activists detained, questioned, and subjected to surveillance and travel bans amid a nationwide crackdown since 2015.

Ding was earlier detained in April 2013 and handed a three-and-a-half year jail term a year later by Beijing's Haidian District People's Court for �gathering a crowd to disrupt public order,� after he called publicly on Chinese officials to reveal details of their wealth, as part of the New Citizens� Movement.