A Japanese daily says a group of 12 North Korean men who were working in the Amur region of the Russian Far East defected to South Korea in September.

According to the Mainichi Daily News Thursday, the 12 men took asylum in the South with help from the Office of the U.N. High Commissioner for Refugees.

The report said the defection marked the first time for a group of North Korean laborers from Russia to take refuge in the South.

Quoting Russian law enforcement authorities, the daily said four more North Korean laborers in the Amur region are seeking to defect to the South. The paper said the Office of the U.N. High Commissioner for Refugees and the South Korean government are currently taking steps to facilitate the four laborers’ defections.

According to the report, Russian authorities are stepping up vigilance amid signs that a growing number of North Korean laborers might seek to take asylum in the South.

Since the days of the former Soviet Union, a large number of North Korean laborers have been working in logging and construction in the far eastern part of Russia based on an accord with the North.