"The proceedings may also end with the adoption of a commitment to take steps to remedy the effects of the infringement which have a detrimental effect on consumers," Poland's Office of Competition and Consumer Protection said in a statement.

"In such case, the Competition Authority may refrain from imposing a fine."

The regulator said it was examining whether emissions sensors installed in VW, Audi, Seat and Skoda cars after 2008 made it possible to artificially lower the nitrogen oxide emissions readings.

The Competition Authority said it found that the actual emissions figures in traffic conditions deviated from the figures given by VW. As a result, the consumers could have been misled by the undertaking, the watchdog said.

(Reporting by Edward Taylor; Editing by Christoph Steitz)