Updated

German officials, Jewish leaders researchers and others have marked the 20th anniversary of the international agreement on returning art looted by the Nazis with new pledges and proposals aimed at breathing new life into the process.

Culture Minister Monika Gruetters said Monday it is Germany's responsibility to improve upon the so-called Washington Principles to restore cultural objects to their original Jewish owners or heirs, noting that their meaning goes beyond the purely financial.

"Behind every stolen object is the fate of an individual," she said.

The Washington Principles were drafted in 1998 to assist in resolving issues related to returning Nazi-confiscated art and were signed by more than three dozen countries — acknowledging that many items did not remain in Germany after the war.

There are also the issues of art sold by Jews fleeing Nazi Germany at rock-bottom prices to finance their escape or to support themselves in their new homelands, and also trying to determine who the rightful heirs are today now that most original owners are deceased.

Ronald Lauder, head of the World Jewish Congress, said many countries are effectively ignoring the Washington Principles, noting specific problems in Hungary, Poland, Spain, Switzerland the Netherlands and France.

For example, France had 60,000 artworks returned to it after the war, of which 15,000 were unclaimed. Some 2,000 of the best were given to French museums, and the rest were sold.

"For 20 years France has not been able to figure out who owns those 2,000 works in their museums," Lauder said. "Somehow the auction house Christie's can review 100,000 pieces every year, but France cannot figure out 2,000 pieces in 20 years."

In Germany, Lauder said the country's "commitment to Holocaust awareness is exemplary" but that there have been problems in the return of Nazi-looted art, which he said are "more institutional than personal."

Among other things, he said that the commission set up to mediate claims has only looked at 15 cases in 15 years, and that navigating the country's "byzantine bureaucracy" is a challenge for anyone looking to research or file a claim.

In response to such criticism, Gruetters said Germany is establishing a "help desk" that will aid anyone interested in filing a claim. In addition, in the past where both a museum and the heir to an artwork had to decide to take a case to arbitration, that is now being changed so that a resolution can be sought by an heir without the museum's agreement.

The single-party consent applies only to museums under federal jurisdiction but officials hope the thousands of state-run museums will follow suit.

Germany also plans to increase its research into finding heirs, and put more information about its collections online so that they can be accessed anywhere in the world for people seeking to find possibly looted property.

Despite frustrations with the process, Stuart Eizenstat, an adviser to the U.S. State Department on Holocaust-era issues who helped negotiate the Washington Principles, said a "very sizable" number of Nazi-looted artworks had been restored to their owners. Austria has restituted 30,000 cultural objects and Germany returned more than 16,000, including 5,746 art objects and 11,700 books, he said.

But, Eizenstat said, many more changes are needed.

Those include all countries recognizing the forced sale of art was a form or plundering Jewish valuables, like Germany does, and that private auction houses follow the lead of Sotheby's and Christie's and institutionalize provenance research of all art they sell.

He also echoed Lauder's comments that all countries that agreed to the Washington Principles need to live up to their commitments.

"There is simply no excuse in the 21st century for coveting Nazi looted art, and it does not speak well for the countries that do so," he said.