"We will continue to review the situation. It's an ongoing monitoring of the market," he was quoted as saying by Handelsblatt.

The German Transport ministry last month said 774,000 Mercedes-Benz vehicles in Europe had been found to contain unauthorised software defeat devices, ordering Daimler to recall more than 200,000 cars in Germany.

Scheuer said the ministry was also monitoring cars from manufacturers outside of Germany, without specifying the brands, but could not take any action itself.

"We are checking vehicles of other manufacturers and seeing that their test values sometimes go through the roof. But we can't do anything because they get the approvals in their own country. That annoys me," he said.

(Reporting by Victoria Bryan; Editing by Robin Pomeroy)