Authorities in Switzerland halted registrations of some new Mercedes-Benz and Porsche vehicles because their diesel engines skirted emissions regulations, Reuters reported Thursday.

Registrations of the small Mercedes-Benz Vito vans equipped with 1.6-liter diesel engines, and Porsche Macan and Cayenne SUVs equipped with 3.0- and 4.2-liter diesel engines, were halted because those engines reportedly flouted emissions rules.

In a statement to Reuters, Mercedes-Benz said the automaker halted exporting the vans in May after it ordered a recall for those vehicles.

Vans and SUVs already on Swiss roads can continue to drive, although they'll need to be fitted with additional equipment to bring those cars into compliance with regulations, according to the report.

The stop-sale brings into view a larger crisis for Germany's automakers struggling to transition from an era of scandalized diesel engines to electric cars. Porsche's corporate parent, Volkswagen AG, has recalled millions of vehicles worldwide for emissions issues in well-publicized incidents, including diesel-powered Cayennes both in the U.S. and abroad.

Last year, Porsche recalled about 22,000 Cayennes equipped with the 3.0-liter diesel engine after German transportation officials announced they had found "irregularities" in the vehicle's software for emissions controls.

In a statement, Porsche said it "has been systematically reviewing all engine and transmission variants and following up on all available indications," but noted that "Porsche itself does not develop and produce diesel engines."

Audi, which is also owned by Volkswagen AG, supplied Porsche with its 3.0-liter diesel engine and its former CEO was jailed earlier this year in relation to the ongoing scandal.

Mercedes is no stranger to controversy either. In the U.S., the automaker faces scrutiny over its diesel software—and lawsuits—and Mercedes has recalled hundreds of thousands of diesel-powered vehicles in Europe.