Gao, who says he had been tortured in the past by the Chinese government, vanished in mid-January and is believed by Amnesty International to have been taken to one of China's notorious "black" jails, The Daily Telegraph reported Tuesday.
"We are intensely fearful for Gao Zhisheng's safety at this time, given the security authorities' long history of abusing him and his family," Sophie Richardson, Asia advocacy director at Human Rights Watch, said in a statement. "He has given detailed accounts of how he was tortured in police custody in the past and he may well be suffering more of the same right now."
Gao, an attorney, incurred the wrath of the government when he defended a member of the outlawed Falun Gong sect who had been sent without trial to a labor camp. He further alienated officials in 2005 when he renounced his membership in the Communist Party and wrote an open letter to President Hu Jintao and Prime Minister Wen Jiabao, urging them to end torture in China, the Telegraph said.