Tina Talarchyk, the Katz heirs’ lawyer in Florida, told JTA in an e-mail that Katz bartered and sold his art to save himself and dozens of family members from the Nazis, who murdered three-quarters of Holland’s 150,000 Jews during the Holocaust.

“Nathan Katz and his collection of art was a target of Hitler and the Nazis long before the occupation of Holland,” said Talarchyk, from the firm Squire, Sanders & Dempsey. “Hitler's grand plan for his Linz Museum was almost as famous and as aggressive as his plan to exterminate Jews.“

Conceived of by Hitler, the museum at Linz was to be the Nazis’ Aryan Louvre. During the course of the war Hitler dispatched art specialists and curators to obtain, often by seizure, thousands of artworks from around the world.

The Katz claim was filed in March but revealed only this month when the Dutch government notified the directors of the museums that today house the disputed objects -- 225 paintings and two tapestries.

The claim could take years for the Dutch looted-art restitution commission to evaluate.

The case highlights one of the most contentious areas in the quest for Holocaust restitution: how present-day European governments evaluate World War II-era sales by Jewish art dealers in Nazi-occupied lands.

It also is a reminder that there are Jewish heirs only now discovering their family treasures in the halls or basements of Europe’s great museums.

“I think on the art issue there has been the least amount of progress out of all the areas of Holocaust-era restitution,” said Gideon Taylor, executive vice president of the Conference on Jewish Material Claims Against Germany.

In a famous case illustrative of the difficulty in Holland of recovering art sold by compulsion during the Nazi era, a Dutch court in 1998 rejected the efforts by Jewish heirs to recover works that Jewish art dealer Jacques Goudstikker sold during the war to save his family.

Holland subsequently established a restitution committee in 2001 to deal with the claims, and in 2006 more than 200 artworks were returned to the Goudstikker heirs.

As one of the only European nations actively seeking potential claimants, the Netherlands in recent years has become a model for restituting Nazi-looted art, Taylor said. By May 2007, the Dutch government processed some 38 claims, mostly in full or partial favor to the claimants, and more than 420 artworks were returned.

This figure dwarfs the estimated 4,000 pieces in Dutch state collections the restitution committee believes were stolen by the Nazis, mostly from Jews.