The South Korean government says it is investigating potential human rights violations during the raid and detention of Korean workers by US authorities.

South Korea has expressed “strong regret” to the US and has officially asked that its citizens’ rights and interests are not infringed during law enforcement proceedings, said a presidential spokesperson on Monday.

More than 300 South Korean workers returned home on Friday after being held for a week following a raid at an electric vehicle battery plant in the US state of Georgia.

The incident has tested ties between the countries, even as South Korean firms are set to invest billions in America under a trade deal to avoid steep US tariffs.

On 4 September, around 475 people – mostly South Korean nationals – were arrested at a Hyundai-operated plant, in what marked the largest single-location immigration raid since US President Donald Trump launched a crackdown on illegal migrants earlier this year.

Immigration and Customs Enforcement (ICE) officials said the South Koreans had overstayed their visas or were not permitted to work in the US.

A South Korean worker who witnessed the raid told the BBC of panic and confusion as federal agents descended on the site, with some people being led away in chains.

Trump has said foreign workers sent to the country are “welcome” and he doesn’t want to “frighten off” investors.