CHICAGO (AFP) - Volkswagen's US sales plunged 25 per cent in November after it suspended sales of diesel vehicles in the wake of an emissions cheating scandal, the embattled German automaker said Tuesday.

VW froze sales of diesel car models in the United States on Nov 4 after new accusations on the use of software that cheats on emissions tests.

Total sales fell by nearly 8,000 vehicles to 23,882 units in November. Sales for the year-to-date were down 4 per cent at 318,484.

Volkswagen has been engulfed in scandal since September, when it admitted more than 11 million vehicles worldwide equipped with smaller 2.0-litre diesel engines had "defeat" software designed to cheat on emissions tests.

US officials have alleged that similar software is on the company's larger 3.0 litre diesel engines, used in Volkswagens, Audis and Porsche SUVs.

The world's No. 2 automaker faces regulatory and criminal investigations in several countries, including Germany and the United States, and potentially billions of dollars in fines.

"Volkswagen is working tirelessly on an approved remedy for the affected TDI vehicles," Mark McNabb, chief operating officer, Volkswagen of America, said in a statement.

"During this time we would like to thank our dealers and customers for their continued patience and loyalty."

The so-called "defeat devices" turn on emissions controls when the vehicle is undergoing a government emissions test, then turns them off under normal operations, allowing illegal amounts of nitrogen oxide to spew into the air.

The scandal has widened, with the German automaker subsequently revealing that it had understated carbon dioxide emissions, including those for gasoline engines, for up to 800,000 vehicles.