Chinese authorities have arrested a scholar who helped blind dissident Chen Guangcheng escape house arrest in 2012, the scholar's wife said Tuesday, in a case that activists say signals a tighter grip on civil liberties.
Guo Yushan, founder of a think tank that did research on business regulations, reform and civil society, was detained in Beijing in October.
Guo's wife, Pan Haixia, told Reuters that Guo was formally arrested on a charge of "illegal business activity" but she did not know what that related to. The Beijing No. 1 Detention Center, where Guo is held, could not be reached for comment.
Guo was instrumental in helping Chen flee from house arrest in his village in 2012. Chen traveled to Beijing where he sought refuge at the U.S. Embassy, sparking a diplomatic row between China and the United States.
Chen was later allowed to travel to the United States.
Authorities shut down Guo's think tank, the Transition Institute, last year.
Guo is an idealistic but media-shy scholar who launched campaigns that drew support from the public, including efforts to raise funds for victims of a tainted milk formula scandal in 2008.
Maya Wang, a researcher at Human Rights Watch, said Guo's detention was "another milestone in the ongoing, severe crackdown on civil liberties" over the past 18 months.
"Although Guo has been at the forefront of China's rights movement, he has also tried to keep a low profile, to remain in that narrowing space without being jailed," she said.
"The fact that he's detained signals further tightening of the authorities' grip on China's civil society."