Another outspoken internet writer, Chen Min - who writes under the penname Xiao Shu - was detained for several hours yesterday amid an ongoing campaign to silence dissidents. Chen, an editorial writer for the state-run China Reform magazine, was taken away from his office at 2.30pm by several unidentified people wearing plain clothes, sources said. He was released after a few hours, but declined to comment when contacted by the South China Morning Post. He was the fifth internet writer to be detained by authorities in the past two weeks. The sources, who are close to Chen, would not speculate about the reason for his detention. A message posted online said Chen sent a message to friends saying the magazine had been told he would be taken away. A senior editor at the magazine contacted yesterday declined to comment. Chen recently posted an article on overseas websites hailing former colleague Zhao Yan , who has been held in custody since September, as a hero. Zhao, a former reporter with China Reform's rural edition, was arrested for leaking state secrets while working as a researcher for The New York Times. In his article about Zhao, Chen said he was not close to him, but admired his courage. Li Baiguang , a farmer activist and a close friend of Zhao, was arrested in Fujian last Tuesday, according to earlier reports. Renowned writers Yu Jie , Liu Xiaobo and Zhang Zuhua were separately taken into custody on Monday last week. They were released the next day. Mr Yu said yesterday the arrests and detentions were part of a campaign to crack down on liberal writers using the internet. 'They are not isolated incidents,' he said. 'The big picture is that they are clamping down on intellectuals and the media.' Mr Yu said he had not been harassed since his release from detention.