"We are aware of multiple fires involving Connecticut vehicles, including some allegedly already repaired through the recall process. This is a serious matter, and we are moving aggressively and responsibly to uncover the facts and to ensure accountability," he said.

The statement cited media reports describing vehicles spontaneously bursting into flames while traveling on streets or while parked.

It noted that in 2015 both Hyundai and Kia began recalls of "several hundred thousand cars" equipped with the Theta II Gasoline Direct Injection engine.

Hyundai and Kia, which together form the world's fifth-biggest carmaker by sales, are fully cooperating with the US authorities in the fire-related investigations, a Hyundai spokesman said. (Yonhap)