SEOUL (Reuters) -Up to 450 workers at a Hyundai Motor ( HYMLF ) facility under construction in Georgia have been detained in a major raid by U.S. authorities that has led to a pause in the project to build a car battery factory.

The raid on Thursday has dealt a setback to the project, which is part of what would be the biggest investment in the state, and illustrates the increasing crackdown by the Trump administration on immigrants and its impact on businesses.

An agent at the U.S. Department of Homeland Security (DHS) said multiple U.S. agencies "conducted a judicially authorised enforcement operation, as we are actively conducting an investigation into unlawful employment practices." "Arrests are being made," Steven Schrank, special agent in charge of Homeland Security Investigations for Georgia, said in a news briefing aired on U.S. television.

The Atlanta office of the U.S. Justice Department agency ATF reported that up to 450 had been detained in a post on X.

South Korea's Foreign Ministry said that "many of our nationals" have been detained during an operation by U.S. immigration authorities and expressed concern about its impact.

"The economic activities of our companies investing in the United States and the interests of our citizens must not be unduly violated during the course of U.S. law enforcement," ministry spokesman Lee Jae-woong said in a statement on Friday.

About 30 South Korean nationals were among those detained, the Yonhap News Agency said.

The battery production facility, a joint venture between South Korean battery maker LG Energy Solution (LGES) and Hyundai Motor ( HYMLF ), was due to start operations at the end of this year, according to LGES.

A spokesperson at the Hyundai-GA battery company said in a statement that it was cooperating fully and that it had paused construction work.

Hyundai Motor ( HYMLF ) said its production of electric vehicles at the sprawling site was not affected.

LG Energy Solution said in a statement it was "closely cooperating with the South Korean government and relevant authorities to ensure the safety of our employees and staff at contractors, and to secure their swift release from detention."

LGES shares dropped 2.3%.

BIGGEST INVESTMENTS IN GEORGIA

In 2023, Hyundai Motor Group and LG Energy Solution announced the $4.3 billion venture to produce EV battery cells, with each company holding a 50% stake. The plant will supply batteries for Hyundai, Kia and Genesis EV models.

The battery factory is part of Hyundai's $12.6 billion investments in the state, including the automaker's just-opened car factory, in what would be "the largest economic development project in the state's history."

A social media video footage showed a man wearing a vest with the letters HIS, an acronym for Homeland Security Investigations, telling workers in yellow safety vests: "We have a search warrant for the whole site. We need construction to cease immediately. We need all work to end on the site right now."

Under President Donald Trump, the Immigration and Customs Enforcement agency, which is part of the Department of Homeland Security, has become the driving force of the Republican leader's sweeping crackdown on migrants, bolstered by record funding and new latitude to conduct raids.

Trump has said he wants to deport "the worst of the worst" criminals but ICE figures have shown a rise in non-criminals being picked up. Rights advocates have denounced such raids.

The U.S. is adding pressure on Korea Inc, one of the major investors in the United States, at a time when Washington and South Korea are at odds over details of a trade deal, which includes $350 billion of investments.