German officials have given scandal-stricken Volkswagen until October 7 to set out a timeline for bringing all its diesel cars in line with national pollution standards.
The federal motor vehicle office (KBA) ordered VW to draw up "binding measures and a timetable" that would show how it will meet emissions standards without resorting to software that rigs test results, Bild am Sonntag reported on Sunday.
The KBA warned that the embattled corporation will be denied approval for the defective models, meaning that they could no longer be sold or driven on German roads.
The German industrial tycoon triggered global outrage after admitting that 11 million of its diesel cars, including 2.8 million in Germany, were fitted with so-called defeat devices that covertly turn off pollution controls when the car is being driven.
The biggest scandal in VW's history has sullied its reputation, left it exposed to billions in fines in the United States as well as knocking about a third off its stock market value in a week and forcing a leadership change.
A Volkswagen spokesman said the company would soon devise an action plan in Germany and "announce when we expect to launch a recall" that would include a software update.
"We are working at full throttle" on the plan, the spokesman said.
Volkswagen in the United States has stopped selling new diesel cars, while Switzerland has ordered a temporary halt to the sale of the group's new diesels. India and Mexico have opened fraud probes, and France and Britain have announced new checks.