The cities where Nazis committed these wrongs carry a special responsibility

Stephan Articus, German Council of Cities.

Germany has already established a website listing some 17,000 works of art plundered by the Nazis from countries conquered during World War II that have ended up in public collections.

Private collections

There are more than 30,000 other pieces that are still being cataloged for the website and another 2,240 works which were seized by U.S. troops at the end of the war and held in Munich.

Since February the website has also invited enquiries from private citizens about art stolen from personal collections.

But despite these efforts only two pieces from federal collections have been returned to their rightful heirs since 1998.

The culture minister said that Germany was still far from the "end phase in dealing with its Nazi past" at the start of the 21st century.

"The attention is larger than ever before," he said.

Now officials are appealing to all of the more than 3,000 museums and 2,300 local libraries in Germany to search their collections for stolen art.

"The cities where Nazis committed these wrongs carry a special responsibility," said Stephan Articus, head of the German Council of Cities.