Taiwan's National Immigration Agency said that a special task force was sent to conduct inspections on 173 sites, and they also arrested 130 Indonesians as well as 118 employers and labor brokers, Taiwan's Central News Agency reported.

The arrests were part of a major operation launched by the Immigration Department in January to arrest migrant workers who have overstayed their visas, it said. Employers hiring foreigners without proper work permits could face fines of between $4,700 and $108,000, according to Taiwan's Employment Service Act.

Taiwan has become a sought-after destination for Vietnamese seeking jobs overseas ever since it lifted a 10-year ban on certain categories of Vietnamese workers in 2015.

Vietnamese workers in the territory can earn $700 - $800 a month, three or four times the typical remuneration in Vietnam.

Last year, 65,000 Vietnamese workers were sent to Taiwan, accounting for nearly half of Vietnam's overseas workforce.

But news of Vietnamese trying to work or stay in the territory illegally is not rare. Last year, 152 Vietnamese in a travel group went missing in Taiwan, making local and international headlines. Many were discovered afterwards, admitting that they tried to stay in Taiwan to work illegally.