BERLIN (REUTERS) - Audi said 2.1 million cars worldwide were fitted with the software that allowed parent Volkswagen to cheat U.S. emission tests.

Some 1.42 million Audi vehicles with so-called EU5 engines are affected in Western Europe, with 577,000 in Germany and almost 13,000 in the United States, a spokesman for Ingolstadt-based Audi said on Monday.

Affected model lines include the A1, A3, A4, A5, A6, TT, Q3 and Q5, the spokesman said.

VW sparked global outrage last week when it admitted that 11 million of its diesel cars are equipped with so-called defeat devices that activate pollution controls during tests but covertly turn them off when the car is on the road.

After the severe battering VW shares took last week in the wake of the revelations, the stock continued to slide on Monday, shedding nearly seven per cent.

According to German media reports at the weekend, Volkswagen ignored warnings from staff and a supplier years ago that the emission test rigging software was illegal.

German authorities meanwhile heaped pressure on the embattled corporate titan, demanding it set out a timeline by October 7 on how it will ensure its diesel cars meet national emission standards without using the cheat technology.

The spiralling scandal has badly tarnished VW's name, left it exposed to up to 18 billion dollars (16 billion euros) in US fines, and wiped a third off its stock market value in a week.

Last Friday, the VW board tapped company insider Matthias Mueller - chief of its luxury sports car brand Porsche - to steer the world's largest automaker out of the wreckage.