Regional offices of Hyundai Motor and its affiliate Kia Motors are being investigated by German prosecutors over allegations that they used defeat devices in their diesel vehicles to skirt government regulations.

The Frankfurt prosecutors’ office in Germany said on Tuesday that around 140 prosecutors and investigators in Frankfurt and Luxembourg were mobilized to raid eight premises of the South Korean automakers in the two countries earlier in the day.

Hyundai and Kia are facing charges accusing them of causing air pollution with emissions-cheating devices. BorgWarner, the owner of the company that allegedly provided the device for the diesel engines in the Hyundai and Kia cars, is also being investigated.

Around 210-thousand diesel Hyundai and Kia vehicles equipped with the illegal software had reportedly been circulated until 2020.

The device is suspected of significantly reducing or turning off emission reductions when the cars are driven, according to the prosecution. Those purchasing the vehicles were not told about the device, it said.