South Korea on Friday expressed “concern and regret” over a major US immigration raid at a sprawling Georgia site where South Korean auto company Hyundai manufactures electric vehicles.

South Korean Foreign Ministry spokesperson Lee Jae-woong described the number of detained South Koreans as “large" though he did not provide an exact figure.

His ministry would not confirm or deny South Korean media reports saying that about 300 South Koreans were detained in Georgia on Thursday.

The Atlanta office of the US Bureau of Alcohol, Tobacco, Firearms and Explosives, which assisted immigration authorities at the site, posed on the social media site X that about 450 people total were apprehended.

Hyundai's South Korean office didn't immediately respond to requests for comment.

The raid targeted one of Georgia’s largest and most high-profile manufacturing sites, touted by the governor and other officials as the largest economic development project in the state’s history.

Hyundai Motor Group, South Korea's biggest automaker, began manufacturing EVs a year ago at the US$7.6 billion plant, which employs about 1,200 people, and has partnered with LG Energy Solution to build an adjacent battery plant, slated to open next year.

In a televised statement, Lee said the ministry is taking active measures to address the case, dispatching diplomats from its embassy in Washington and consulate in Atlanta to the site, and planning to form an on-site response team centred on the local mission.

“The business activities of our investors and the rights of our nationals must not be unjustly infringed in the process of US law enforcement,” Lee said. (AP)