Audi has discovered problems with emissions with another 60,000 cars.
The announcement is another setback to its parent company, Volkswagen, more than 2 years after it first admitted to cheating US diesel exhaust tests.
Audi said it had stopped deliveries of A6 and A7 models with a certain type of diesel engine after finding a previously unidentified problem with emissions software. It did not give details of the problem.
A person familiar with the matter said 60,000 cars would have to be recalled for a software update, taking the total number of vehicles with Audi engines to be recalled over the"dieselgate" emissions scandal to more than 900,000 vehicles.
Volkswagen has recalled millions of vehicles in total and paid out billions of dollars in fines since it admitted in September 2015 to using illegal "defeat device" software that masked the level of pollution emitted by its diesel engines.
Having announced a multi billion-dollar investment in electric vehicles, and a new chief executive only last month, Europe's largest car maker has been looking to move on from the biggest business crisis in its history.
Audi's announcement came a day before its annual share holder meeting, where it was hoping to focus on its electric car plans.
The German transport ministry said earlier on Tuesday that the KBA motor vehicle authority had summoned Audi for a formal hearing about its A6/A7 diesel models.
"The KBA has requested a hearing on suspicion the Audi V6TDIA6/A7 models have been fitted with an illegal defeat device," the ministry said in a statement.
German magazine Der Spiegel was first to report that Audi had discovered the problem.
Prosecutors in Munich, which in the past have raided Audi's headquarters and are investigating 18 of its current and former employees, said they would widen their probe to include the affected A6/A7 models.
