FILE PHOTO: A Mercedes Benz Vito. September 26, 2014. REUTERS/Fabian Bimmer/File Photo

ZURICH (Reuters) - Swiss authorities have halted registrations of some new Mercedes-Benz DAIGn.DE Vito and Porsche PSHG_p.DE Macan and Cayenne vehicles which had diesel engines that disguised emissions levels, the Astra roads agency said on Wednesday.

The move will affect vehicles imported from Aug. 17. Vehicles already registered in Switzerland may continue to operate, but must be retrofitted, Astra said in a statement.

Mercedes Vitos with 1.6-litre diesel engines, Porsche Macans with 3-litre diesel engines and Cayennes with 4.2-litre diesel engine are affected by the action. All have Euro 6 emission norms, which refers to the emissions standards these engines are required to meet.

Daimler said it had stopped exporting the Vito model after German authorities in May ordered a recall and halt to new registrations for the vehicle. This affected 24 Vito vehicles destined for Switzerland, a spokesman for the German manufacturer said in an emailed statement.