North Korea's catalog of abuses against its own people within the secretive country's tightly controlled borders has been widely reported. But Kim Jong Un's regime is also believed to be pocketing huge sums from tens of thousands of its citizens who are sent abroad to toil in forced labor conditions, the United Nations says, according to CNN News.

The laborers are made to work as long as 20 hours a day without enough food and under constant surveillance, according to a new report from Marzuki Darusman, the UN special rapporteur on human rights in North Korea.

He told a news conference Wednesday, October 28, that the practice has become more visible in recent years and that "the numbers have grown."

"I think it reflects the really tight financial and economic situation in the North," Darusman said.

The overwhelming majority of the workers are employed in North Korean allies China and Russia, according to the report. But the rest are spread across a range of countries in Asia, the Middle East, Africa and Europe.

CNN reported on the practice in May, highlighting the case of a North Korean man who worked on a construction site in Kuwait for five months without receiving any pay. He eventually managed to escape his minders and take asylum in the South Korean Embassy.

His story chimed with those of other escaped workers who have told rights groups of long hours, little or no pay, no freedom and harsh living conditions.

Those who do get paid are believed to receive between $120 and $150 a month, but their employers "pay significantly higher amounts" to the North Korean government, the U.N. report said.