Authorities in the southwestern Chinese megacity of Chongqing have committed around a dozen activists to psychiatric facilities after they took part in a demonstration last Friday in the city's Yangjiaping district, RFA has learned. Around 70 activists took to the streets of Yangjiaping last week in protest at forcible evictions and demolitions by city authorities. Protesters Pan Bin, Liu Gaosheng, Xiao Chenglin, Tan Min, and He Chaozheng were later detained alongside several others whose names couldn't be confirmed, fellow activists said. According to an open letter in protest at the move, the government is increasingly using psychiatric "treatment" as a means to incarcerate local critics and activists. It said activists Deng Guangying, Zhang Fen, Liu Deying and others had already been incarcerated in mental healthcare facilities last year in Chongqing. The letter expressing concern for their safety and calling for their release had garnered around 100 signatures by Tuesday. Chongqing-based activist Guo Xingmei said petitioners have formed a group to campaign against the use of psychiatric detention. "They are still in the psychiatric hospital, although the police brought Tang Yunshu out again after she went in," Guo said. "She is at home now." "But He Chaozheng, Liu Gaosheng, Xiao Chenglin, Tan Min and a few others have been "mentally illed'," Guo said. "They all had to go for a "check-up'." Involuntary treatment Tang said in a brief interview with RFA on Tuesday that she was initially subjected to involuntary psychiatric "treatment" last June. "I was locked up and persecuted in the Chongqing Jinzishan Mental Health Hospital on June 1, 2017," she said. "I was given a psychiatric check and a diagnosis." Tang was diagnosed with "paranoid personality disorder," defined by diagnostic manuals as a "an unwarranted tendency to interpret the actions of other people as deliberately threatening or demeaning." But according to the open letter, Tan, Liu, Xiao, He and the other detainees were protesting the government's forcible takeover of their land and demolition of their homes, suggesting that their interpretations of threat weren't "unwarranted." They were only referred for psychiatric "treatment" once they lodged official complaints about the loss of their homes. "They are all wise healthy citizens with no mental illness whatsoever," the letter said. "They shouldn't have been "mentally illed'." Chongqing petitioner Li Qun told RFA that the local authorities are increasingly using such tactics against their critics. "Take Tang Min, for example," Li said. "The[criminal] case against her was sent back for further investigation by the prosecution, so they put her in a mental hospital." "They diagnosed her as mentally ill, and then there is Tang Yunshu, who they locked up for 10 months, and have now released with no charges, but who also has a psychiatric diagnosis." "Chongqing is sending all of its rights defenders to psychiatric hospitals for diagnosis right now," Li said. "A lot of rights activists and petitioners have signed the letter saying they don't want to be mentally illed, in the hope of raising awareness." The Chongqing protest comes as authorities in the southern province of Guangdong confined a rights activist to a psychiatric hospital in spite of her appearing to lack any symptoms of mental illness. Continuing collusion Zhang Qi was committed to the Guangzhou Baiyun Mental Rehabilitation Hospital in the Baiyun district of Guangdong's provincial capital after being incommunicado for several months, her fellow activists told RFA. Despite protections promised by a Mental Health Law passed by China in 2013, the country's medical profession has continued to collude with the authorities in carrying out psychiatric incarceration of critics of the ruling Chinese Communist Party, a rights group has said in a recent report. The practice of locking up those who challenge the government in mental institutions has become an endemic rights abuse in the country's legal system, and authorities have increasingly used the tactic against rights activists and dissidents as a way of imposing indefinite periods of detention on them without the need for a trial, according to the Civil Rights and Livelihood Watch report. The Mental Health Law was aimed at protecting mental health service users from misdiagnosis and involuntary medical treatment in China's state-run psychiatric hospitals. But the use of state psychiatric institutions to restrain critics of the ruling Chinese Communist Party is still widespread, according to the Hubei-based group's annual report for 2017. "The widespread and persistent creation of "psychiatric patients" by the Chinese authorities not only constitutes a grave violation of international human rights conventions, but also violates the provisions of the Chinese Constitution, Criminal Law and Mental Health Act that respect the protection of civil rights," the group said.