Porsche said it had made a voluntary notification to the authority as "a pre-cautionary measure" a year ago, regarding conformity issues with individual vehicles.

"The current procedure has already been able to find no conformity deviations in the large majority of vehicles," a Porsche spokesperson said in an emailed statement.

The number of vehicles affected was "far less" than 1% of the Porsche fleet, the spokesperson said, adding no decision had yet been reached and that proceeding were at an early stage.

KBA was not immediately available for comment.

(Reporting by Kirsti Knolle and Jan Schwartz; Editing by Riham Alkousaa and David Evans)