Germany's Transport Ministry has reportedly asked the European Commission of the EU to investigate exhaust emissions of Fiat Chrysler vehicles.

Reuters reported that the move by the German government follows the testing of several makers' vehicle exhaust emissions by the German KBA (road vehicle authority).

The German initiative to test vehicles of multiple carmakers followed the breaking of VW's so-called 'dieselgate' scandal last year.

Reuters reported that the direct approach to the EU follows KBA concerns over FCA vehicles - raised with Italian authorities earlier this year, but subsequently rejected by the Italians.

According to Reuters, the letter to the European Commission, said that tests by German authorities on the Fiat 500X, Fiat Doblo and Jeep Renegade could prove the "illegal use of a device to switch off exhaust treatment systems" and urged the Commission to consult with Italian authorities to resolve the issue.

However, Reuters reported that the Commission has responded that it's a matter for the two countries concerned. "It is first and foremost a dialogue between the two member states concerned, with an obligation to keep the Commission informed and the possibility for the Commission to facilitate a solution if no agreement can be found," the European Commission said in a statement.

FCA has said that its cars conform to current emissions rules and do not contain defeat devices.