ROME (Reuters) - New tests carried out on Fiat Chrysler (FCA) vehicles during Italy’s emission-cheating investigation have found no illegal engine software, Italy’s Transport Minister Graziano Delrio said on Wednesday.

The Fiat 500X is seen during its North American debut at the Los Angeles Auto Show in Los Angeles, California November 20, 2014. REUTERS/Lucy Nicholson

Delrio made the comments after a preliminary report from the ministry showed FCA vehicles were initially allowed to skip key tests during the investigation launched in the wake of the Volkswagen VOWG_p.DE diesel emissions scandal.

In that report, presented to a European parliamentary committee in October but never officially published, results were missing from an on-road measurement phase and a reversed version of the EU’s standard lab test for three of the seven FCA models tested.

All seven FCA models also lacked data for an “Artemis” test that adjusts the EU lab regime to reflect urban driving styles. The three skipped tests are typically used to help unmask defeat devices by preventing them from detecting the test.

Maurizio Vitelli, an official in charge of the ministry’s motor vehicle unit, told Reuters earlier on Wednesday additional tests had been carried out on the FCA models and a final report will be published within days.

He said the Artemis test was not part of checks required to assess whether a vehicle complied with regulations and the examiners could decide whether to apply it at their own discretion.

“There was no deliberate omission in having done that test only on some of the vehicles, it was the examiners’ choice to add it or not,” he said.

Asked whether he ruled out the existence of illegal defeat devices in FCA vehicles, Vitelli said he did not “exclude anything, but we have not found any.”

FCA already faces a U.S. criminal investigation for alleged emissions manipulation and German accusations that it, like VW, used “defeat devices” to confound nitrogen oxide (NOx) tests.

The Italian-American group on Monday also became the third carmaker after VW and Renault to be referred to French prosecutors over the scandal. FCA has denied breaking any laws.

In his comments on Wednesday, minister Delrio told a parliamentary hearing that Rome had sent a separate report to German authorities refuting their allegations and showing that three FCA models -- Fiat 500X, Jeep Renegade and Fiat Doblo -- were compliant with regulations.

Delrio said the European Commission, which is mediating in the dispute, was supportive of Italy’s position.