A special United Nations envoy has presented a report critical of North Korea to the U.N. Commission on Human Rights. The report says that those who flee North Korea to seek food become political refugees because they risk severe punishment when they go home.

A new United Nations report calls on North Korea to reform its justice system, which it blames for "egregious" human rights abuses.

Vitit Muntharborn, the U.N. special rapporteur on North Korean human rights, presented the report Tuesday to the U.N. Human Rights Commission in Geneva.

North Korea does not acknowledge his mandate, and has refused him entry to the country.

Professor Vitit told the commission he relied mainly on testimony from North Korean defectors in Mongolia and other countries. Based on those interviews, he says he found that among other abuses, the North Korean government regularly imprisons people without trial, tortures prisoners and uses forced labor.

He acknowledged in his testimony that tens of thousands have left North Korea mainly to escape severe food shortages, but he says they become de facto refugees because of dangers they face if they are sent home.

"Those who left because of hunger are also under threat of persecution if they are to be sent back to the country of origin because they usually leave without permission," he said.

The 53-nation commission is expected to vote on a North Korean human rights resolution next month. It is not yet considering economic sanctions against North Korea, also called the DPRK, a stance Professor Vitit supports.

"I personally prefer a constructive dialogue-and-influence approach, and particularly to urge friends of DPRK to use their leverage very strongly," he said.

Pyongyang's ambassador to the United Nations rejected the report, saying it resembles propaganda used by countries hostile to North Korea. However, China and Cuba did not voice support for North Korea at this year's session, in what may be a sign of Pyongyang's growing isolation.

An estimated 100,000 North Koreans are thought to be in China or Mongolia, hoping to reach South Korea after passing through Southeast Asia. However, that journey may be getting more difficult.

Laos and Thailand announced this week they will step up patrols along their borders to prevent the entry of asylum seekers. Officials with the United Nations High Commission for Refugees say the move is not specifically aimed at North Koreans. Instead, it is part of broader regional diplomacy aimed at curbing human trafficking, as well as flows of other refugee groups crossing borders in greater numbers.