The Vietnamese nationals, whose identities have not been disclosed, have been placed under criminal investigation for charges of forging official documents and violating the Immigration Control Act, the Yonhap News Agency reported.
The investigation found that the group of Vietnamese had asked a Chinese broker to forge registration certificates for aliens in an attempt to hide their status and avoid the crackdown on illegal immigrants by local police.
They are alleged to have paid $442 to $531 per fake certificate.
The investigation began after officers at the Incheon International Airport discovered 13 fake alien registration certificates dispatched via international express mail from China between late last month and early this month.
Based on the recipients’ address and other personal information, immigration officers hunted for a 20-year-old Vietnamese man who was staying illegally in Incheon, west of Seoul, in early March.
Nine other Vietnamese citizens were later captured from Seoul and neighboring provinces. The suspects had been staying illegally in South Korea for one to six years, police said.
The Ministry of Justice’s Korea Immigration Service said it is tracking down three more Vietnamese suspects in the case.
South Korea is one of the largest labor export markets for Vietnam. However, the number of migrant workers who reside in the country illegally is relatively high.
There were over 45,398 Vietnamese migrant workers in South Korea by the end of June 2018, the majority of them registered under the Employment Permit System, according to official labor reports.
The Vietnamese also account for 30-40 percent of around 200,000 illegal foreign workers in South Korea.