A new report says thousands of Chinese each year are committed to mental institutions against their will, often for punishment or political purposes.

The Chinese Human Rights Defenders group says those locked up for alleged mental illnesses are frequently subjected to forced medication, violence, and other mistreatment such as electrical shocks. It says many have no obvious mental disorders.

The China-based NGO says citizens can be “disappeared” for an indefinite period of time “based on the existence or mere allegation of a psychosocial disability by family members, employers, police, or other state authorities.”

It says the system is often exploited by government officials to lock up activists, dissidents, and perceived troublemakers, as well as by wealthy individuals who want to get rid of opponents.

The report said that institutionalized people are denied the right to make decisions regarding their own fate, including admission, discharge, and treatment. They are also often restricted from communicating with the outside world, including family members and legal counsel.

The report, titled “The Darkest Corners: Abuses of Involuntary Psychiatric Commitment in China” urges Beijing to conform to the U.N. Convention on the Rights of Persons with Disabilities, which China ratified in 2008.

The U.N. Committee on the Rights of Persons with Disabilities is set to issue its first review of China's compliance with the treaty next month.