The car workers arrested in one of the largest ever US workplace immigration raids had violated their visitor visas, officials say.
Immigration and Customs Enforcement (ICE) said 475 people, mostly South Korean citizens - were found to be illegally working at a Hyundai plant in the US state of Georgia on Thursday.
People on short-term or recreational visas are not authorized to work in the US, ICE said, adding that the raid was necessary to protect American jobs.
South Korea, whose companies have promised to invest billions of dollars in key US industries in the coming years, partly to avoid tariffs, has sent diplomats to Georgia, and called for its citizens' rights to be respected.
The arrested workers were being held at an ICE facility in Folkston, Georgia, until the agency decides where to move them next.
Of those detained, 300 are reported to be Korean nationals. Hyundai said in a statement that none of them were directly employed by the company.
In a statement on Friday, the ICE office in the city of Savannah said the raid was part of an active, ongoing criminal investigation.
Homeland Security Investigations (HSI) Special Agent Steven Schrank welcomed the investment by foreign companies in the US but emphasized the importance of adhering to legal channels for employment.
South Korea's foreign ministry has responded with concerns over the rights and interests of its citizens during US law enforcement operations.
The raid not only raises questions about immigration enforcement but also about its potential impact on US-Korea relations amidst ongoing international negotiations.
