Some 2.1 million Audis affected worldwide include 1.42 million in western Europe, with 577,000 in Germany, and almost 13,000 in the US.
Czech-based Skoda said 1.2 million of its cars were involved, but has yet to give a country or model breakdown.
Separately, German prosecutors started a probe against VW's former boss.
Former chief executive Martin Winterkorn will be investigated over "allegations of fraud in the sale of cars with manipulated emissions data," German authorities said on Monday.
The Audi models affected  include the A1, A3, A4, A5, A6, TT, Q3 and Q5 models, a spokesman told the Reuters news agency.
VW said last week that 11 million cars within the group could be affected.
The scandal was revealed after the US Environmental Protection Agency found that some diesel cars were fitted with devices that could detect when the engine was being tested and could change the car's performance to improve results.
The German company apologised for breaching consumers' trust, and on Friday announced that Matthias Mueller was replacing Martin Winterkorn as chief executive. Mr Mueller promised a "relentless" investigation to uncover what went wrong.
There were also unconfirmed reports on Monday that senior R&D heads working across the car group had been suspended. Reuters said the suspensions involved staff from the Audi, Porsche and the VW brands.
Meanwhile, Volkswagen shares continued to fall, closing down 7.3%. They are now down about a third since the scandal broke.
The scandal has badly tarnished VW's name, left it exposed to up to $18bn in US fines, and wiped a third off its stock market value in a week.
German authorities have demanded that VW set out a timeline by 7 October on how it will ensure its diesel cars meet national emission standards without using cheat technology.
There were widespread German media reports at the weekend that the government ignored warnings two years ago that VW was using the software. However, on Monday, a government spokesman denied this.
11 million
Vehicles affected worldwide
â‚¬6.5bn Set aside by VW
$18bn Potential fines
No. 1 Global carmaker in sales
I'm a VW owner - what should I do?
What next for VW?
Car emissions tests: Not fit for purpose?
VW boss Winterkorn's highs and lows
VW scandal explained

The airline has been loss-making in all but two years since 2003, when it was bought by the States for £5m.
Previously the Treasury and Resources Department had expected Aurigny to return to profit by 2016, but that has now been revised to 2018.
Its report, which will be voted on next month, said the "ongoing loss-making position" was a "cumulative result of a number of key factors".
Cabernet Ltd, the holding company for Aurigny Air Services and Anglo Normandy Engineering, operates through borrowing guaranteed by the States.
The debt to be written off is £19.9m accumulated from 2003 to 2014 and the expected £5.3m loss up to 2017 - £2.3m in 2015, £1.5m in 2016 and £1.5m in 2017.
It will be paid out of the island's capital reserve.
Aurigny performance in 2014
Aurigny has borrowed more than £50m, guaranteed by the States, to support its business and the purchase of new aircraft.
The proposals also include allowing the department to be able to provide short-term borrowing to Cabernet to cover the annual losses.
The department's report said it was "firmly of the view" retaining the company "remains overwhelmingly in the Bailiwick's strategic interest", although it said this included recognising the "risk that ongoing financial support will be required".
Treasury Minister Gavin St Pier said it was a "strategic asset" acquired to secure the route to Gatwick, which "is as important now as it was in 2003".
Audi and Skoda say they have a total of 3.3 million cars fitted with the software that allowed parent company Volkswagen to cheat US emissions tests.
[NEXT_CONCEPT]
Aurigny could have debts of more than £25m paid off by Guernsey's government.