Key Points

Cho made the remarks as he presided over an emergency meeting on the immigration crackdown, confirming that more than 300 out of 457 people who were taken into custody are South Korean nationals.

"We are deeply concerned and feel a heavy sense of responsibility over the arrests of our nationals," Cho said at the start of the meeting, attended by two vice ministers, officials from the ministry and overseas missions, reports Yonhap news agency.

"We will discuss sending a senior foreign ministry official to the site without delay, and, if necessary, I will personally travel to Washington to hold consultations with the U.S. administration," he said.

Cho said President Lee Jae Myung has instructed officials to make all-out efforts to swiftly resolve the matter, stressing that the rights and interests of South Korean nationals and the business operations of South Korean companies investing in the United States must not be infringed upon.

Second Vice Foreign Minister Kim Ji-na expressed regret and concern over the crackdown during a meeting with acting U.S. Ambassador to Seoul Joseph Yun on Thursday, Cho said.

U.S. authorities carried out a search warrant at an electric vehicle battery plant construction site operated by HL-GA Battery Co., the joint venture between Hyundai Motor Co. and LG Energy Solution Ltd. in Bryan County near Savannah on Thursday.

They described the raid as a criminal probe into alleged unlawful employment practices.

U.S. President Donald Trump said on Friday the arrested people are "illegal aliens" and the immigration officials were "just doing their job."

Steven Schrank, a special agent with Homeland Security Investigations (HSI) for Georgia, said the individuals in custody include those who came in through a visa waiver program that bans them from working, or had overstayed their visas.

Most of them are being held at a detention centre in Folkston, Georgia.

HL-GA Battery Co. said it is fully cooperating with the authorities and has paused construction to assist their work.

U.S. authorities have called the raid "the largest single site enforcement operation in the history" of the HSI.

In a statement Saturday, LG Energy Solution said it has suspended all business trips to the U.S. and has instructed employees currently visiting the U.S. to stay in their accommodations or return home immediately.

The company's chief human resources officer will depart for the U.S. the following day to address the issues on site, the firm said.

"We will make every effort to promptly resolve the situation, including ensuring the speedy and safe return of all employees," the firm noted.

Of those in custody, 47 have been confirmed as LG Energy Solution employees, while the others are related to HL-GA Battery.

Most were reportedly dispatched to carry out final construction work, such as electrical installations, ahead the plant's planned completion next year.

- IANS