BERLIN: Investigators in Germany, Switzerland and Italy are searching several sites over suspicion that vehicles built by Fiat Chrysler and Iveco groups may have been fitted with illegal defeat devices, as the "dieselgate" emissions scandal widened.

Coordinated cross-border raids were being carried out at "ten commercial properties" across the three countries, the public prosecutor for the German state of Hesse said in a statement.

Fiat Chrysler and Inveco's parent company CNH Industrial later issued statements confirming that their offices were among those searched. Both said they were "providing full cooperation" with officials.

The automobile and industrial vehicle groups are suspected of having installed so-called "defeat devices" into their vehicles in order to illegally cheat on emissions tests.

Such devices make vehicles appear to spew fewer harmful pollutants in the lab than on the road.