Russia has been giving work permits to North Korean labourers despite a United Nations ban on the practice, which funds Pyongyang's nuclear weapons programme.
On September 11, the UN forbid countries from authorising new employment contracts for North Koreans as part of sanctions meant to starve the Kim Jong-un regime of money following a string of nuclear blasts and missile tests last year.
But documents seen by The Telegraph indicated that Russia has continued to approve work permits for North Koreans months after the UN ban, reports Telegraph UK.
A decree on foreign workers posted by the labour ministry on December 6 approved positions for hundreds of North Koreans, mostly manual labour jobs like painter, bricklayer, carpenter or mechanic.
The list gave companies permission to hire 1,237 North Koreans just in the Amur region near Russia's border with the Hermit Kingdom.
Russia has approved more jobs for North Koreans this year, according to a report on Thursday by the Washington-based think tank Centre for Advanced Defence Studies.
While Pyongyang is cut off from the international financial system, it is able to make up to $2.3 billion in hard currency a year by sending some 100,000 or more workers abroad, according to estimates. Up to 80 per cent of them go to China and Russia, where they are employed in what the UN has called "slave-like conditions" and give up to 90 per cent of their wages to Kim Jong-un's regime.
The United States sanctioned a Russian bank and two North Korean companies on Friday for "illicit revenue streams" to Pyongyang, and US secretary of state Mike Pompeo said renewed activity at a missile factory were were "inconsistent" with Mr Kim's supposed promise to denuclearise.
So far in 2018, documents show the Russian labour ministry has given at least 12 companies permission to hire 806 North Korean workers, the defence studies report said.
The director of Soyuz Stroi, a construction company that has employed North Koreans, told The Telegraph that he was still hiring citizens of the country this year.
"We are doing this, we've hired new ones, and we have the old ones," Malsar Khuseinov said.
Asked about the UN hiring ban, he said "that's a question for our government".
"They don't come here on our own," he said. "You need to call Putin."
The North Korean embassy in Moscow declined to comment when reached by The Telegraph.
On Friday, a foreign ministry spokeswoman denied that Russia was violating the UN resolution, saying it was giving work permits to North Koreans whose contracts were signed before September 11, 2017.
But the number of new work permits and job listings by companies who have received them raises doubts that all this employment was agreed before the ban.
Companies in the Moscow region that were given permission by the labour ministry to hire North Koreans have been advertising similar work on the Moscow employment centre website as recently as July. At least two of them were looking for Korean-language translators.
An email to an address listed for one of the companies bounced back, while a phone number listed for two others was not ringing on Friday.
The Wall Street Journal saw copies of work permits issued to North Korean workers as recently as June even though the labour ministry has said there were no applications this year. US officials are looking in to potential violations of the UN sanctions by Russia and China, it said.
The Americans have accused the two countries of helping Pyongyang import oil products in excess of UN caps.
The defence studies report also found evidence that Russian firms were partnering with North Korea in apparent contradiction of the UN's demand that joint ventures with North Korean individuals or companies cease operations by January 2018.
For instance, a North Korean company called Zenko, the Russian name for the Genco worker export company sanctioned by the United States in 2016, is listed a shareholder in the Sako Rynma LLC joint venture, according to a corporate registry.
Russia has appeared to be making maximum use of the UN's grace period, which says that all North Korean workers must be sent home only by December 22, 2019, in hopes it could be cancelled.
The head of the far east development ministry said that Vladimir Putin had issued a decree to "extend" work permits for North Koreans to December 22, 2019.
His deputy previously said "we expect that important political changes in Korean cooperation will start" by the time that deadline comes up.
North Koreans in Russia often work six or more days a week and live in cramped construction wagons or dormitories under under close guard. The defence studies report estimated that 30,000 of them are currently working in Russia for an average monthly wage of £230 (NZ$443).
Previously many of them worked in logging camps that were described as "open-air prisons" by one North Korean who escaped.
Contractors have said North Koreans helped build the World Cup stadium in St Petersburg, where at least one died on site.
"It's not just slavery conditions, it's a slavery psychology and a slavery situation," said activist Svetlana Gannushkina, who has helped several North Koreans in Russia seek asylum here or other countries. "The victims agree to his situation, because they are raised this way, and those who start to resist are incredibly strong."
In addition, North Korea operates at least 83 restaurants in China, which are estimated to bring in $10 million annually for Pyongyang and have been linked to its overseas weapons procurement operations, according to the report.
Since the UN ban, several restaurants have reopened or transferred to Chinese ownership and continued operations with the same North Korean staff, it said.