Hyundai, South Korea's top automaker, is investigating child labor violations in its U.S. supply chain and plans to "sever ties" with Hyundai suppliers in Alabama found to have relied on underage workers, the company's global Chief Operating Officer Jose Munoz said on Wednesday.

An investigative report in July documented children, including a 12-year-old, working at a Hyundai-controlled metal stamping plant in rural Luverne, Alabama, called SMART Alabama.

Following the report, Alabama's state Department of Labor, in coordination with federal agencies, began investigating SMART Alabama. Authorities subsequently launched a child labor probe at another of Hyundai's regional supplier plants, South Korean-operated SL Alabama, finding children as young as age 13.