It is believed that around 150,000 North Koreans are sent abroad each year to work, bringing in billions of dollars in income to the North Korean government. The workers have to hand over much of their earnings to a North Korean “captain” in what one worker called “Party Duty.”

For the last two years, an undercover team of journalists with the BBC has been investigating the situation for North Korean laborers sent to China, Russia, and Poland. Most North Korean men were reluctant to speak on camera, though one man who spoke anonymously to a reporter said that “You’re treated like a dog here, and you have to eat dirt.”

“You have to give up being human,” he added.

He also explained that ten years ago the amount of money North Korean laborers had to give to “captains” was 15,000 roubles ($260) a month. Today that amount has doubled.

At one shipyard in Szczecin, Poland, the undercover team posed as a recruitment agency, meeting with the foreman of the nearly 800 North Korean workers who are welders and laborers there. The foreman said that the men are stationed in Poland only to work, though they only take unpaid holidays and will work without breaks when there are deadlines.

The Polish workers at the shipyard, the man explains, “Work eight hours a day and then go home.” The North Korean laborers “are not like the Polish,” he said. “We work as long as we have to.”

The North Korean embassy in Warsaw says that its citizens are working in compliance with EU regulations and Polish law. At the same time, the Polish government claims it has carried out regular inspections and has found no evidence that workers’ earning are being sent back to North Korea.

The former North Korean Deputy Ambassador to the UK, Thae Yong Ho, says even though the small amount of money the North Korean men are able to send home “no doubt helps their families in North Korea,” he argues that this should not be a reason for other countries to drop sanctions against the regime as it continues to develop its nuclear program.

The United Nations passed a resolution in December that would put an end to North Korean laborers being sent abroad, but host countries have been given two years to comply.