North Korea has sent over 50,000 people abroad to work in forced labor conditions, a United Nations researcher said Wednesday. The totalitarian nation earns between $1.2 billion and $2.3 billion annually through this system, Marzuki Darusman, the special rapporteur on human rights in North Korea, said, citing one estimate.

North Koreans are sent to work in countries across Asia, the Middle East, Europe and Africa and a large number of them work in Russia and China, Darusman said in a report to the U.N. General Assembly and at a news conference , according to the Associated Press.

The people work mostly in mining, textile and construction industries for up to 20 hours a day, are paid a monthly income of between $120 and $150 and are underfed, Darusman added.

Employers pay "significantly higher amounts" to the North Korean government, Darusman reportedly said. According to Darusman, companies that employ the North Korean workers "become complicit in an unacceptable system of forced labor." The workers provide a new source of money to North Korea, which is in a "really tight financial and economic situation.”

Darusman noted that the practice became more obvious lately and "the numbers have grown," CNN reported. He added that the overall human rights situation in North Korea remained "dire.”