A total of 12 Vietnamese women were arrested in Tainan, a city in southwest Taiwan, on Tuesday for alleged prostitution or links to a vice network.
The Tainan branch of the National Immigration Agency (NIA) acted on a tip-off and apprehended the women, who were working at massage parlors, Central News Agency reported.
But the rest of the women had entered the country on tourist visas and visas issued on arrival.
Huang said nine of the women were arrested at the three massage parlors run by Nguyen, while two others were detained at an airport the moment they arrived.
Some NT$580,000 (US$18,820) in cash was confiscated by the authorities during the raids.
Authorities will investigate Nguyen for offenses linked to sexual morality. The 11 others will be deported after investigations are completed.