At least 20 people have been detained by Chinese authorities in a roundup of suspects linked to the publication of a letter calling on President Xi Jinping to resign, human rights organizations said on Saturday.
Wen Yunchao, an influential blogger and government critic, said on Friday that his 65-year-old mother, 72-year-old father and 41-year-old younger brother were taken away by police in Guangdong province, southern China, on March 22.
In a move that highlighted Beijing's increasingly confident intervention against critical voices overseas, police targeted New York-based Wen, an influential Communist Party critic with more than 220,000 Twitter followers.
Wen, 45, denies any involvement in the dissemination of the anonymous letter posted March 4 on Chinese media website Wujie (Watching) News, demanding Xi step down.
The open letter, signed "loyal Communist Party members" and accusing President Xi of building a "personality cult", has since been deleted from the Internet.
Wen said on March 17 that his father and brother were forced to contact him and pressure him to disclose what he knew. Wen's brother was told he would lose his job as a local government driver if Wen didn't comply, human rights groups said.
Earlier this week, the editor-in-chief of the Wujie News website, Ouyang Hongliang, was taken in for questioning along with other staff members, associates told US-based broadcaster Radio Free Asia.
Citing an anonymous source in the Wujie News newsroom, the BBC reported that up to 16 staff – six from editorial and 10 from technical support - have been taken away.
On March 15, Jia Jia, a Beijing-based freelance writer, disappeared while preparing to board a flight from Beijing to Hong Kong. He was released on Friday.
His lawyer Yan Xin told the Committee to Protect Journalists that he had been detained on suspicion of drafting the letter.
"Detaining family members of independent journalists living outside China is nothing but blackmail. We call for the immediate and unconditional release of Wen Yunchao's parents and brother," said Robert Mahoney, deputy executive director of the Committee to Protect Journalists, in a press release.
"China is clearly resorting to such tactics at home to intimidate critics abroad."