UPDATE: 4:45 pm ET: Volkwagen said Tuesday as many as 800,000 more vehicles, other than the 11 million already having the bogus software, "could be affected." Matthias Müller, the VW CEO, said the automaker "will stop at nothing and nobody" to get to the bottom of the scandal. VW did not immediately identify the vehicles in question.

Original story:

US pollution regulators said late Monday that the Volkswagen emissions-test cheating scandal now includes Porsche, the brand that was run by VW's new CEO.

The Environmental Protection Agency said the cheating software to rig pollution tests was in 3.0 liter diesel engines in Audis and Porsches for model years 2014 to 2016.

"VW has once again failed its obligation to comply with the law that protects clean air for all Americans," Cynthia Giles, assistant administrator at the EPA's enforcement unit, said in a statement.

The agency said these diesel models contain the so-called "defeat device" cheating software: the 2014 VW Touareg; the 2015 Porsche Cayenne; and the 2016 Audi A6 Quattro, A7 Quattro, A8, A8L, and Q5.

That the scandal has now hit Porsche calls into question VW's new chief executive, Matthias Müller. Before recently being elevated to VW's top position to clean up the emissions scandal, he was the head of Porsche.

VW, however, disputed the EPA's assertion. The automaker said vehicles with the 3.0 liter diesel V6 engines "had a software function which had not been adequately described in the application process." The company said it is working with US pollution regulators to "clarify" the situation.

"Volkswagen AG wishes to emphasize that no software has been installed in the 3-liter V6 diesel power units to alter emissions characteristics in a forbidden manner," VW said.

The EPA countered:

VW's software on these vehicles includes one or more Auxiliary Emission Control Devices (AECD) that the company failed to disclose, describe and justify in their applications for certificate of conformity for each model. Every manufacturer must apply to EPA for and be approved for a certificate of conformity for each model each year, otherwise it is illegal to introduce the cars into commerce. An AECD designed to circumvent emissions test is a defeat device.

Porsche also said it is innocent. "We are surprised to learn this information. Until this notice, all of our information was that the Porsche Cayenne diesel is fully compliant," Porsche said in a statement.

In September, VW admitted that as many as 11 million diesel vehicles, from years 2009 to 2015, had the cheating software installed. The software would rig emissions tests by forcing the engine to pollute less during testing but allow the car to function much better and pollute more on the road. The US government said that the software allowed the vehicles to spew toxic nitrogen oxide up to nine times beyond EPA standards.

For its part, VW says it's a victim of "rogue" engineers who tinkered with the software unbeknownst to VW executives. The company insists this "was not a corporate decision."

The automaker has set aside as much as $7.4 billion to address the scandal, which includes criminal investigations on both sides of the pond.

The latest revelations affect about 10,000 cars in the US.