Reuters said Friday that recent fires in General Motors and Hyundai Motor's electric vehicles are linked to LG batteries produced at two Asia plants.

The report said that documents filed by GM and Hyundai with the U.S. safety regulator show how the two automakers separately identified the same cause of the battery fires in their newest electric vehicles, tracing them to similar manufacturing defects in battery cells made at at least two plants operated by a unit of LG Chem.

GM and Hyundai have linked the fires to lithium-ion battery cells supplied by LG Energy Solution, an LG Chem subsidiary and one of the world’s largest battery manufacturers. The cells were produced at LG plants in South Korea and China.

According to Reuters, an LG spokesperson said Friday that together with its client and partners, LG is actively working to ensure that the recall measures are carried out smoothly.

In South Korea, shares of LG Chem dropped to a nine-month low on Friday, reflecting investor concerns about the hefty cost of recalling defective batteries.