BERLIN, Germany: Mercedes-Benz has been warned that Germany could issue a recall for some autos found to have pollution-defeat devices installed into their software.

Defeat devices can be activated when an auto is undergoing emission tests. It can alter an auto's normal operating levels to ensure passing the test, only to return to operating levels that do not violate emission standards.

According to media reports, the German transport authority KBA sent a letter to Mercedes-Benz detailing three devices found in cars to defeat environmental testing.

The KBA warned Mercedes-Benz that they were obligated to remove such devices from their autos or have the autos banned from EU roads, based upon an earlier ruling by the European Court of Justice.

Meanwhile, Mercedes-Benz has said it would comply with requests from the KBA and would update auto software to eliminate the defeat devices.

Mercedes-Benz said it will provide a list of autos with the defeat software to the KBA.

"We currently assume that software updates for vehicles that may be affected by a final decision on the functionalities ... have already been developed and are available in the field," the company added.