An environmental activist protests in front of Germany's federal administrative court, before they decide whether German law provides a legal basis for cities to ban diesel cars to help reduce air pollution, in Leipzig, Germany, February 27, 2018. The words read "Diesel exhaust kills." REUTERS/Fabrizio Bensch

FRANKFURT (Reuters) - Any diesel bans would likely take two years to put in place by which time the affected cities may have found other ways to reduce pollution, Hendrik Wuest, the transport minister of the German state of North-Rhine Westphalia, said.

“There will be new anti-pollution plans. Those can be challenged in court... By the time everything is decided it will be 2020,” Rheinische Post newspaper quoted Wuest as saying in an interview published on Saturday.

By that time, a package of measures will have further reduced the levels of toxic nitrogen oxide in the air, he said.

“Bans are avoidable” in North Rhine-Westphalia, he added.

A federal court ruled on Tuesday that German cities can ban the most heavily polluting diesel cars from their streets, a move that could accelerate a shift away from the combustion engine and force manufacturers to pay to improve exhaust systems.