Detainees at Cambodian government-run drug rehabilitation centres suffer "sadistic violence" such as electric shocks, forced labour and rape, a human rights group said Monday.
Human Rights Watch (HRW) called on Cambodia to close at least 11 centres around the country where it said people are often arbitrarily sent without reasonable cause, suffer grave abuses and are denied access to a lawyer.
"Many detainees are subjected to sadistic violence, including being shocked with electric batons and whipped with twisted electrical wire," said a 93-page report from the group.
"Arduous physical exercises and labour are the mainstays of supposed drug 'treatment'," it added.
Rights groups have made allegations about abuse at Cambodia's drug rehabilitation centres and UN health officials have questioned their treatment methods in the past.
"Individuals in these centres are not being treated or rehabilitated, they are being illegally detained and often tortured," said Joseph Amon, director of the health and human rights division at HRW.
"These centres do not need to be revamped or modified; they need to be shut down."
HRW also alleged detainees were forced to have sex with staff and to donate blood, were fed rotten or insect-ridden food and chained while standing in the sun as physical punishment.
The centres, run by various branches of the Cambodian state including police and the ministry of social affairs, detained nearly 2,400 people in 2008, according to the report.
Detainees were arrested for drug use and vagrancy, but were also frequently rounded up in police sweeps of people considered "undesirable" in advance of national holidays or international meetings, it added.
Government data revealed that more than 500 of the detainees were aged under 18, HRW said, and one former 16-year-old detainee named M'noh described staff members using electrical wire for whippings.
"[A staff member] would use the cable to beat people... On each whip the person's skin would come off and stick on the cable," he said in the report.