March 1 (UPI) -- Five North Korean workers may have suffocated to death during a gas leak near the Ural mountains, according to a South Korean press report on Thursday.
An official at Moscow's Ministry of Emergency Situations who spoke to Yonhap anonymously said the accident occurred at a construction site container box that was serving as a dormitory for the workers.
The five North Koreans were found dead inside the container.
A local investigator said the men may have burned coal after an electric heater had broken down.
"It appears the victims died after choking to death on the toxic fumes," the Russian investigator said, according to Yonhap.
The deceased North Koreans were working for the Russian construction company Salvia, the report states.
Temperatures plunged to -4 degrees Fahrenheit as the workers struggled to keep warm.
The North Koreans were likely members of a large workforce, authorized by the Russian and North Korean governments to work in labor-intensive industries like construction, farming, fisheries or logging in the Russian Far East and Siberia.
It is estimated between 35,000 and 37,000 North Korean workers are deployed in Russia despite international sanctions against their North Korean labor.
Russian press caused confusion on Thursday by initially reporting the victims as South Korean nationals, according to Yonhap.
Moscow continues to maintain friendly ties with the relatively isolated regime, and Russian visits to North Korea continue to be highlighted in Pyongyang's state media.
KCNA reported this week a "delegation of the Far Eastern Branch of the Russian Academy of Sciences led by academician Valentine Sergiyenko," had visited North Korea on Monday.