Seoul, South Korea - The South Korean government said Monday it would review whether there were any human rights violations when hundreds of its citizens were detained in a massive raid in the US.

Around 475 people, mostly South Korean nationals, were arrested at the construction site of a Hyundai-LG factory making electric vehicle batteries in Georgia on September 4.

The raid was the largest single-site operation conducted since President Donald Trump launched an all-out war on immigrants in the US.

Images of the workers chained and handcuffed shocked South Korea. After delicate diplomatic negotiations, the detained workers were released and flown back to Seoul.

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Some of them told local media about appalling conditions during their arrest, including alleging they were held without being informed of their rights.

When asked about the allegations, the presidential office in Seoul said it was conducting a "thorough review".

"Both our side and the US are checking if there were any shortcomings in the measures taken and companies are also looking into it," presidential spokeswoman Kang Yu-jung told a press briefing.

"Together with the company concerned, we are conducting a more thorough review into possible human-rights infringements."

One of the workers told Yonhap News Agency that their rights were not read when they were arrested.

The worker also told the agency that ICE agents mocked them with remarks about "North Korea" and "rocket man" – an insult Trump has previously used about Pyongyang's leader Kim Jong-un.

South Korean President Lee Jae Myung called the raid "bewildering" and warned it could have a chilling effect on future investment.

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South Korean companies "can't help but question whether setting up a plant in the US is worth the potential risks," Lee said.

In what seemed to be a response, Trump insisted on Sunday that foreign workers are "welcome."

"I don't want to frighten off or disincentivise Investment into America by outside Countries or Companies," he wrote on Truth Social.