Malaysia has decided to stop issuing work permits for North Korean laborers in the wake of the apparent assassination of the estranged half-brother of North Korea’s leader Kim Jong Un in Kuala Lumpur earlier this year, according to Malaysian government sources.

Axar.az reports citing Japan Times.

Malaysia and North Korea used to have friendly relations, but they deteriorated sharply with the killing of Kim Jong Nam at Kuala Lumpur International Airport in February. A number of North Koreans were implicated by Malaysian police in the alleged plot.

The unilateral economic sanctions measure imposed by Malaysia is in line with the request of the United States for countries to cut off sources of funds that could be used by North Korea for its nuclear and ballistic missile development programs.

North Korea has dispatched tens of thousands of workers to China, Russia, Southeast Asia and elsewhere to earn foreign currency needed to fund its weapons programs. If other countries follow Malaysia’s lead, it could deal a serious blow to North Korea.

U.S. Secretary of State Rex Tillerson, in remarks delivered Tuesday at a ceremony to unveil an annual report on human trafficking, said an estimated 50,000 to 80,000 North Koreans have been sent overseas, primarily to Russia and China, as “forced laborers.”

Many of them work 20 hours a day and most of their pay is confiscated by their government, which “receives hundreds of millions of dollars per year from the fruits of forced labor,” Tillerson said. “Responsible nations simply cannot allow this to go on, and we continue to call on any nation that is hosting workers from North Korea in a forced labor arrangement to send those people home,” he said.

The U.S. House of Representatives passed a bill in May to strengthen sanctions targeting foreign companies hiring North Korean workers, while President Donald Trump’s administration is trying to persuade other countries to minimize their ties with North Korea and block its sources of funding.

Malaysian police say the North Korean leader’s half-brother died on Feb. 13 after two women smeared the extremely toxic nerve agent VX on his face.

Suspicions quickly arose that it was an organized assassination by North Korea. And amid the resulting diplomatic row, both governments expelled each other’s ambassador and imposed tit-for-tat exit bans on each other’s nationals.

At the time, about 1,000 North Korean workers had been working in Malaysia, mostly at coal mines and construction sites in the state of Sarawak on Borneo. Most subsequently returned home.

According to diplomatic sources, all workers at a North Korean restaurant located in the center of Kuala Lumpur departed after their work permits expired in May and were not renewed. The restaurant closed at the same time.