A Christian human rights lawyer who was kidnapped and tortured by Chinese authorities in 2011 has disappeared once again, sparking outrage among rights groups.

According to China Aid, Jiang Tianyong, a human rights attorney, was visiting the family of another imprisoned defense lawyer, Xie Yang, in Changsha, Hunan, when authorities abducted him. Over a week later, Jiang has not been heard from, and his family has not received information on his whereabouts or on what charges he is being held.

"Jiang Tianyong has been disappeared since the evening of Nov. 21," his wife, Jin Bianling, told Radio Free Asia. "I haven't been able to get in contact with him."

Jiang, a former lawyer who was disbarred in 2009, was previously arrested for defending figures such as dissident Gao Zhisheng and blind activist Chen Guangcheng, and working a number of religious freedom cases, including the Falun Gong, according to the Hong Kong Free Press.

At the time of his disappearance, Jiang was working to publicize China's crackdown on lawyers despite facing constant harassment from authorities. During his initial detention, he was routinely tortured and beaten by prison guards, according to numerous reports.

Jiang's disappearance has drawn widespread condemnation, with NGO Amnesty International urging the public to write to the Chinese authorities and demand his release.

Patrick Poon, China researcher at Amnesty International, told HKFP: "I believe Jiang Tianyong's disappearance is related to his endless efforts to help other detained human rights lawyers and their families. It's alarming to see that even solidarity action can lead to him being silenced and disappeared."

He added, "If he is detained by the Chinese authorities simply because of his assistance provided to fellow detained human rights lawyers and their families, it means that anybody can be detained if they speak up on human rights."

Four family members of lawyers detained in China's crackdown last year, along with 61 Chinese lawyers, issued a statement on Jiang's disappearance on Monday.

"This makes us extremely suspicious that Jiang's disappearance may be due to relevant departments taking him into administrative detention or taking other kinds of coercive measures - even if this is the case, we urge [the authorities] to notify his family members immediately, to avoid causing unnecessary panic to them and to society."

The statement also urged Public Security departments to investigate Jiang's case and said it would be unacceptable if he was subjected to criminal prosecution merely because he met with Chen or because he accompanied her to enquire about her husband.

Hong Kong legislator Kwok Ka-ki of the Civic Party and several others staged a protest on Monday near the China Liaison Office, calling for the release of Jiang, Liu Feiyue - the founder of a rights watch website who also went missing recently - and other rights defenders in China.

"Rights defense is not a crime! Release rights defenders immediately!" they chanted.

Amnesty International reports that the hundreds of human rights lawyers caught up in China's crackdown have been referred to in Chinese state media as part of a "major criminal gang", troublemakers or otherwise had their characters assassinated. Many of them face charges of trying to subvert state power.