The Ministry of Public Security on Sunday raided a facility in Ho Chi Minh City suspected of making thousands of CDs and DVDs of pirated movies and music every day.
Police caught many workers duplicating discs illegally at the site in District 12, hidden behind a scrap metal shop.
The workers confessed that the business had been running for several years using equipment worth "millions of dollars."
They usually worked from 8 p.m. until early morning in soundproof rooms to avoid getting caught.
The group allegedly produced about 15,000 CDs and DVDs a day, which would then be distributed to wholesalers.
Police are now looking for the owner. They have not taken any measure against the workers.