Chinese authorities have detained the leader of an outspoken Chinese writers' group since Monday without giving any explanation, his wife said Friday.
Shi Xiaoli told The Associated Press that police gave no reason when they took her husband Zhao Shiying after searching their home and taking computers and documents.
Zhao is the secretary-general of the Independent Chinese PEN Center and a signer of Charter 08, a daring call for reform in China, whose co-author, Liu Xiaobo, was sentenced to 11 years in prison on Christmas Day for incitement to subvert state power.
Other signers of Charter 08 have been harassed, and Zhao's detention comes amid tightening controls in China on online and other forms of expression.
Zhao, who uses the pen name Zhao Dagong, called his wife Friday afternoon to say he was in good condition.
"He's with state security agents," she said by phone from the southern city of Shenzhen. "He's never been taken away for this long."
Shenzhen's public security bureau asked that any requests about Zhao's case be faxed and did not respond to questions.
The Independent Chinese PEN Center has pushed for the release of Liu, a well-known literary critic.
"We are concerned that Zhao Dagong will become the latest writer to suffer," the Hong Kong-based writers' group said in a statement.
The Independent Chinese PEN Center is affiliated with International PEN, a global group that promotes freedom of expression. The Independent Chinese PEN Center also speaks up for Chinese writers who are imprisoned or harassed.
"We call on the government to release Zhao Shiying immediately, and to stop propagating this campaign against all citizens of China who are simply expressing themselves peacefully in accordance with their rights under Chinese and international law," K. Anthony Appiah, president of the PEN American Center, said in a statement.
Charter 08 called for expanded political freedoms and the end to Communist Party dominance. More than 300 people, including some of China's top intellectuals, signed it before it was made public.