(Adds Spiegel report)
BERLIN, Oct 5 (Reuters) - Authorities in Berlin are looking at imposing bans on older diesel cars on 20 streets including major routes in the German capital, local broadcaster rbb said on Friday.
An administrative court in Berlin is due to hear a case brought against the city-state of Berlin by the DUH environmental group next Tuesday.
DUH wants the city to reduce air pollution by banning diesel vehicles up to the Euro 4 standard from the end of 2018 and for Euro 5 standard cars from September 2019. The latest standard is Euro 6.
The rbb report cited internal documents on cleaner air from the Berlin Senate Administration for Environment, Transport and Climate Protection. It said those documents showed almost one in six drivers in Berlin would be affected. The department could not immediately be reached for comment.
The federal German government this week outlined plans to cut pollution from diesel vehicles by asking carmakers to offer owners trade-in incentives and hardware fixes, prompting objections from environmental groups and grudging concessions from the industry.
The German Environment Agency (UBA) does not think the measures agreed at the diesel summit will suffice to avoid driving bans in all German cities, magazine Der Spiegel reported on Friday.
It said the UBA - Germany's main environmental protection agency - was particularly sceptical about whether the trade-in incentives to get owners of older diesel cars to switch to newer, cleaner ones would be effective.
Volkswagen's admission in 2015 that it cheated U.S. diesel emissions tests led to the discovery that diesel vehicles from several manufacturers routinely exceeded pollution limits in normal driving conditions, prompting a regulatory crackdown.
Environmental groups have been encouraged by a court ruling in February that allowed cities to ban older diesel cars.
A ban is due to take effect in Frankfurt, Germany's financial capital, from February. The city of Hamburg this year voluntarily blocked diesel models that fail to meet the Euro-6 emissions standard from selected trunk roads. (Reporting by Michelle Martin Editing by Keith Weir)