Sept 15 (Reuters) - More than 300 South Korean workers who were detained in last year's immigration raid ‌at a Hyundai electric-vehicle manufacturing plant in Georgia are ‌challenging the U.S. government, CNN reported on Tuesday.

Hundreds of workers, most of ​whom are South Korean nationals, were arrested in a raid at a Hyundai Motor plant by U.S. authorities last September.

Administrative claims on behalf of the workers, a mandatory step before ‌a federal lawsuit, have ⁠started to be filed with nine federal agencies, the CNN report said citing a lawyer ⁠representing the claimants.

The Department of Homeland Security, Immigration and Customs Enforcement, Customs and Border Protection, the FBI and the Departments of ​Justice ​and Labor were among the ​agencies, it added.

The raid targeting ‌the Georgia plant, operated through a joint venture between Hyundai and South Korea's LG Energy Solution was described as the largest single-site enforcement operation in the U.S. Department of Homeland Security's history.

The video and photos of workers shackled at ‌the wrists, waist and ankles sent ​shockwaves through South Korea, a key ​Asian ally of ​the United States.

Workers' phones were confiscated, and some ‌were unable to inform their ​families back home ​until their eventual release.

Hyundai did not immediately respond to a Reuters request for comment outside regular business hours. ​The U.S. Department ‌of Homeland Security did not immediately respond to a ​request for comment.

(Reporting by Hyunsu Yim in Barcelona ​and Ananya Palyekar in Bengaluru)