SEOUL, Sept 10, 2025 (BSS/AFP) - A chartered plane will depart Seoul for the United States on Wednesday to repatriate hundreds of South Korean workers detained in a sweeping immigration raid, flagcarrier Korean Air told AFP.

US immigration officials detained 475 people, including hundreds of South Korean workers, during a raid on Thursday at a Hyundai-LG battery plant being built in the southern state of Georgia.

Officials in the United States called it the largest such raid on a single site carried out so far under President Donald Trump's nationwide anti-immigration crackdown.

A Korean Air Boeing 747-8I, which seats over 350 passengers, is scheduled to take off from Seoul at 11:00 am (0200 GMT) Wednesday, a company representative told AFP.

"A timeline for the return flight has not been finalised," she added.

The Yonhap news agency reported that the plane would leave the United States with the workers at 3:30 am Thursday (1830 GMT Wednesday), citing diplomatic sources.

Seoul's foreign minister Cho Hyun left for Washington on Monday for further talks, calling the mass detention of the country's nationals a "grave situation" and pledging to secure the workers' swift return "in good health".

Before his departure, Cho told South Korean MPs that "a tentative agreement" had been reached with US authorities to ensure the detained workers would not face penalties, such as a five-year ban on re-entry.

"I can tell you that negotiations are going well" to prevent such restrictions from being imposed, he said.

In addition to being a key security ally on the Pacific Rim, South Korea is Asia's fourth-biggest economy and a major automaker and electronics producer, and its companies have multiple plants in the United States.

Seoul has also heeded Washington's repeated call for global investment in the United States during tariff negotiations.

The site of the raid is a $4.3 billion joint venture between two South Korean firms -- Hyundai and LG Energy Solution -- to build a battery cell manufacturing facility in Georgia.

Experts say majority of detained South Korean workers were likely to have been on visas that do not allow for hands-on construction work.