BERLIN, Feb. 27 (Xinhua) -- The Federal Administrative Court in Leipzig has approved the unilateral enactment of municipal driving bans for certain types of diesel vehicles in landmark ruling for German cities on Tuesday.

The judges hereby rejected legal appeals launched by the states of North-Rhine Westphalia and Baden-Wuerttemberg after the cities of Stuttgart and Duesseldorf were successfully sued by the German environmental organization "German Environmental Relief" (DUH) for failing to sufficiently protect citizens from traffic-related pollution.

While the ruling cannot impose driving bans itself, it empowers municipal authorities to do so out of their own initiative in order to lower levels of nitrogen oxide emissions.

The states of North-Rhine Westphalia and Baden-Wuerttemberg had argued unsuccessfully that the removal of diesel vehicles from traffic could only occur on the basis of new federal legislation which applied equally across Germany.

"We have enforced the possibility of diesel bans from today onwards", the victorious DUH director Juergen Resch told press after the court announcement.

Growing calls for such radical action were first heard in Germany in the wake of the global "dieselgate" scandal and gained renewed momentum after Berlin admitted that at least 20 German cities would fail to comply with European Union (EU) limits for nitrogen oxide emission levels by 2020.

According to the Federal Environmental Agency (UBA), diesel cars are responsible for more than 50 percent of nitrogen oxide emissions. Human exposure to this form of air pollution has been associated with pulmonary diseases in several medical studies. The EU has threatened to sue Germany before the European Court of Justice (CFEU) unless the situation is addressed swiftly.

The verdict by the Federal Administrative Court on Tuesday now will force the cities of Stuttgart and Duesseldorf to re-assess their adequacy of their proposed measures to comply with binding EU clean air regulations. However, the ruling also makes allowance for transition phases and exceptional circumstances which at least partially relieve affected cities of their legal duty to impose bans.

In the case of Stuttgart specifically, the court mandated evaluating a phased introduction of driving bans which would affect older diesel vehicles first. The presiding judge Andreas Korbmacher noted that cities would not be responsible for financially compensating the owners of cars whose value depreciated as a result.

"Certain losses in value must be accepted", Korbmacher said. He added that it was within the power of state governments to prevent a "patchwork" of regulations by establishing unified standards for their respective regions.

German media recently reported that the federal government in Berlin wants to enact new legislation within the course of the year which would empower municipal governments to impose driving bans which only apply to selected roads as opposed to cities and towns as a whole.

However, the proposal falls far short of demands by German cities for the creation of a nation-wide, and hence more easily-enforceable, "blue placard" which would grant cars with relatively low emissions privileged access to areas with high population density.