SEOUL, South Korea - A United Nations envoy says North Korea is estimated to hold up to 200,000 people in political prisons, a sharp increase from a decade ago.

Special UN rapporteur on North Korean human rights Marzuki Darusman gave the estimate in his report to the UN General Assembly. He cited a comparison of satellite images published by human rights groups.

Darusman did not say how many North Koreans were believed to be in political prisons in 2001. South Korea estimates that North Korea holds 154,000 political prisoners in six large camps across the country.

Darusman said recent satellite images indicate "a significant increase in the scale of the camps."

North Korea has one of the worst human rights records. But Pyongyang claims it has no such problems.