"The Office of the High Commissioner for Human Rights in Nepal calls again on the Communist Party of Nepal (Maoist rebels) to stop all parallel 'law enforcement' activities, especially incidents of torture and ill treatment," said Sandra Beidas, the Kathmandu-based officer-in-charge of the group.

Last month, the rebels announced they were starting "security patrols" around the capital Kathmandu, citing police failure to curb crime.

They detained more than 190 people, with all except 10 released after investigations. However some of those had been tortured, the rights group said.

"OHCHR staff have witnessed serious injuries among those held captive ... consistent with claims of ill treatment and torture," the group said in a statement.

The group noted the rebels had repeatedly made commitments to halt abductions but "OHCHR-Nepal ... confirmed abductions of 39 individuals in the districts of Bhaktapur, Lalitpur and Kathmandu in October alone."