California regulators ordered Volkswagen Wednesday to recall some diesel vehicles equipped with emissions-cheating software in coming months as the German company's pollution scandal widens.

The California Air Resources Board said it had notified Volkswagen Group of America to recall all VW, Audi and Porsche vehicles equipped with 3.0-liter diesel engines in the model years 2009-2015 that were sold in California.

The company has 45 business days to submit its plan to begin the process of recalling and repairing the illegal emissions software, said CARB, part of the California Environmental Protection Agency. The western state has some of the toughest environmental regulations in the United States.

"This action is the result of an admission by officials at Audi A.G., manufacturer of all the engines involved, that the vehicles contain three auxiliary emissions control devices," CARB said in a statement on its website.

The recall will involve between 15,000 and 16,000 3.0-liter diesel vehicles, Dave Clegern, a CARB spokesman, told AFP.

In its letter to Volkswagen, the agency noted that though the 3.0 liter engine was developed by Audi, it has been used by VW and Porsche in their Touareg and Porsche models since 2009.

"Audi, Porsche and VW all independently certified their products and, therefore, individually responsible for their violations and future recall actions," it said.

The so-called "defeat device" is software that turns 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 federal Environmental Protection Agency, which is probing the VW emissions scandal with CARB, said last Friday that Audi had told US regulators that three-liter diesel models since 2009 contain the auxiliary emissions control devices (AECD).

Volkswagen has been engulfed in scandal since September, when it admitted more than 11 million vehicles worldwide equipped with smaller 2.0-liter diesel engines had the pollution-spoofing software.

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.

The world's number-two automaker faces regulatory and criminal investigations in several countries, including Germany and the United States, and potentially billions of dollars in fines.

Volkswagen Group of America was not immediately available to comment on the CARB order.