Plans by China to legalise the secret detention of suspects have alarmed activists, who say the move would give authorities free rein and lead to a surge in cases.
The proposed change to China's criminal law would make it legal to detain suspects for up to six months at a time without charge in secret locations away from police stations and official prisons.
The practice -- known as "disappearance" -- became a popular method of silencing dissidents after February, when calls for Arab-style protests began appearing on Chinese websites.
Activists fear it could become even more widespread if the changes are passed and say the new legislation is a tacit acknowledgement that Chinese police are engaging in illegal practices.
"The Chinese government’s proposed legislation would give the security apparatus free rein to carry out ‘disappearances’ lawfully," Sophie Richardson, China director at Human Rights Watch, said in a statement.
"Legalising secret detention puts detainees at even greater risk of torture and mistreatment."
In April, a UN human rights panel expressed rare public concern about the arrests of Chinese activists and lawyers, warning that "enforced disappearance is a crime under international law."
Among them was the internationally known artist and outspoken government critic Ai Weiwei, who was held without charge in a secret location for nearly three months this year before being released and charged with tax evasion.
Ai's sister has said the artist was kept in a tiny cell and watched constantly by two guards who worked three-hour shifts and even watched him when he showered.
Other high profile cases include 2010 Nobel Peace Prize laureate Liu Xiaobo, who disappeared into police custody for over a year before he was finally tried and sentenced to 11 years in prison for subversion in December 2009.
And three prominent human rights lawyers, Teng Biao, Liu Shihui and Li Tiantian have this year given separate accounts of their detentions.
Teng told how police turned up at the home of a friend he was visiting, dragged him into a van and took him away. He was released that night, but later taken away again and held incommunicado for more than two months.