Last week the carmaker admitted to using engine software to rig diesel car emissions tests in the US, with the software present in around 11 million vehicles worldwide.
Guenther Scherelis, a spokesman for the commercial vehicles unit, is said to have confirmed a report in Hannoversche Allgemeine Zeitung that 1.8 million of its vehicles were affected.
According to Reuters, the manufacturer is now looking at recalling all 11 million vehicles involved, which also includes 5 million VW brand cars, 2.1 million Audis and 1.2 million Skodas.
Dr Herbert Diess, CEO of the Volkswagen Passenger Cars brand, has previously stressed: "We are working at full speed on a technical solution that we will present to partners, to our customers and to the public as swiftly as possible. Our aim is to inform our customers as quickly as possible, so that their vehicles comply fully with regulations. I assure you that Volkswagen will do everything humanly possible to win back the trust of our customers, the dealerships and the public."