North Korea is still operating six Stalinist-style labour camps holding 154,000 inmates, a South Korean lawmaker said on Saturday.
Yoon Sang-Hyun, from the ruling Grand National Party, said the North had had 10 camps holding about 200,000 prisoners until the late 1990s when it closed down four of them amid mounting international criticism.
"Currently, it holds 154,000 prisoners in six places," he was quoted as saying by Yonhap news agency.
He cited a government report presented to the National Assembly.
Seoul had reportedly been aware of the camps since 2005 but had not disclosed the information for fear of harming inter-Korean relations, the conservative Dong-A daily said.
North Korea denies holding any political prisoners. Its official media say there are no human rights issues in the communist state where everybody leads "the most dignified and happy life."
Inmates at the gulags are reportedly forced to work more than 10 hours a day and denied access to medical care, receiving only 100 to 200 grams (four to eight ounces) of food rations, while the North Korean food ration for children of up to age four is set at 234 grams.