FRANKFURT — German motor vehicle authority KBA has summoned Audi for a formal hearing about whether its diesel-engined A6/A7 models have been fitted with a previously unknown defeat device, Germany’s Transport Ministry said on Tuesday.

In Germany, around 30,000 vehicles diesel vehicles fitted with 6-cylinder diesel engines may have been fitted with an illegal software emissions device, German weekly magazine Spiegel reported earlier Tuesday.

“The KBA has requested a hearing on suspicion the Audi V6TDI A6/A7 models have been fitted with an illegal defeat device,” Germany’s Transport Ministry confirmed in a statement.

Audi was not immediately available for comment.

Around 60,000 vehicles worldwide have been fitted with the suspect V6TDI engines, the transport ministry said, adding that the pan-European road certification of the Audi models in question was issued in Luxembourg.