Authorities in the Chinese capital are holding a documentary filmmaker who was making a film about now-detained dissident Xu Zhiyong.



Chen Jiaping, who has also used the name Chen Yong, was detained in early March on suspicion of "incitement to subvert state power," according to multiple reports.



His wife published an extract from an letter she wrote to him on his 50th birthday, in which she links his detention to the unfinished documentary about Xu.



Chen is being held incommunicado at an unknown location. An officer who answered the phone at the police department in Changping, a suburb of Beijing, declined to give out any information.



"Where is he now?" the officer asked. "There are more than 20 police stations in Changping," before saying he couldn't check a detainee without knowing where they were detained.



An employee who answered the phone at the Haidian district police department made a similar response, before adding: "It's not one of ours, anyway."



In her letter, Chen's wife hit out at the reason for her husband's detention, saying that no written article had ever upended society.



"Our country can't be subverted by a work of art, and the people can't be subverted by a documentary that hasn't even been released yet," she wrote. "I don't believe that any institution would be able to place limits on artistic creativity in a free and democratic country."



Bei Ling, executive secretary of Independent Chinese PEN said the order to pursue anyone connected to Xu likely came from the highest ranks of the Chinese leadership.



"I think it's because Xu Zhiyong has ... angered people in highest echelons of leadership in China, which is why people involved in making this documentary were also detained," Bei said. "But a filmmaker trying to understand something isn't participating in it."



"The Xu Zhiyong documentary wasn't going to be a record of his calling on Xi Jinping to step down; it was more of a portrait of a civil rights campaigner," Bei said.



CPJ decries 'absurd' detention

Interview requests made via friends to Chen's wife had met with no response at the time of writing.



The New York-based Committee to Protect Journalists (CPJ) called for Chen's immediate and unconditional release.



"Detaining Chen Jiaping for filming a documentary on a subject the Chinese government doesn’t like is absurd," CPJ program director Carlos Martinez de la Serna said in a statement.



"Chinese authorities should drop all charges against Chen Jiaping, release him immediately, and allow him to continue his work," he said.



The CPJ said the authorities have repeatedly denied Chen’s wife’s requests to see her husband, and have put pressure on her to keep quiet about his case.



On Dec. 26, police from the eastern province of Shandong coordinated with other police nationwide to arrest human rights activists and participants who gathered in Xiamen, Fujian, in early December to organize civil society actions and plan nonviolent social movements in the country.



Several people who attended were detained on suspicion of "incitement to subvert state power” and “subversion of state power." The latter charge carries a minimum 10-year prison sentence.



Among them was New Citizens' Movement founder Xu Zhiyong, who was eventually detained in Guangdong province on subversion charges.



While their families waited to learn their whereabouts, other rights activists who had gone to the Xiamen event, and even those indirectly connected to them, fled the country or went on the run.



Reported by Hsia Hsiao-hwa for RFA's Mandarin Service. Translated and edited by Luisetta Mudie.