“Illegal 'defeat devices' were identified” in some 4,000 Cayenne and 15,000 Macan cars sold by the high-end Volkswagen subsidiary in Germany, a spokesman for the KBA vehicle licensing authority told AFP, confirming a report from Der Spiegel.

The news weekly reported that almost 60,000 vehicles worldwide — 53,000 Macans fitted with 3.0 litre diesel engines and 6,800 4.2-litre Cayennes — had software built into them designed to reduce harmful emissions under test conditions compared with real on-road driving.

Macan diesels — which Porsche claimed were in compliance with the latest and strictest “Euro 6” emissions standards — included five such “defeat devices”, Spiegel said, even following a 2016 software update designed to reduce pollution.

Spokespeople for Porsche did not immediately comment on the recall when contacted by AFP.

Germany's keystone car industry remains in the focus of the media and criminal investigators almost three years after Volkswagen's September 2015 admission of manipulating 11 million diesel cars worldwide to fool emissions checks.

VW has paid out more than €25 billion in fines, buybacks and compensation since its “dieselgate” scandal broke.

And former top executives are under investigation over whether they failed to inform investors quickly enough about the looming threat to the firm.

So far only middle-ranking managers have been arrested on suspicion of direct involvement in the manipulation.

An unnamed Porsche manager was taken into custody by Stuttgart prosecutors in April, with German media reporting the man arrested was Joerg Kerner, former head of engine development.

 Among other German car firms, high-end BMW and Mercedes-Benz maker Daimler have both had their offices raided by investigators searching for evidence of possible cheating.

BMW recalled some 12,000 cars in February after admitting they contained software that allowed the engines to release more harmful emissions on the road than in the lab — but insisted the software was installed by mistake.