BERLIN (AFP) ― Identifying the rightful owners of a vast trove of art looted by the Nazis will be an enormous task potentially complicated by the German authorities’ insistence on discretion, experts said Wednesday.

The more than 1,400 artworks found last year stashed in the Munich apartment of Cornelius Gurlitt, son of a powerful Nazi-era art dealer, represent perhaps the largest discovery of missing 20th century art in Europe since World War II.

But beyond its scope, its richness is staggering, with masterpieces by Picasso, Matisse and Renoir along with previously unknown works by modernist painters Marc Chagall and Otto Dix among its gems.

Focus, the magazine that broke the story this week, estimated the value of the collection at one billion euros ($1.3 billion), a figure German investigators have declined to confirm.

The German government and state prosecutors in the southern city of Augsburg assume that the Nazis stole the art from Jewish collectors, bought it from them for a pittance under duress, or seized it from museums as part of a crackdown on avant-garde “degenerate art.”

Gurlitt’s father Hildebrand was one of a handful of dealers tasked by Nazi propaganda chief Joseph Goebbels with selling such works abroad in exchange for hard currency.

The Holocaust Art Restitution Project posted a list on its Facebook page Wednesday of artworks seized from Hildebrand Gurlitt by U.S. forces immediately after World War II that were returned to him in 1950 after intensive lobbying.

Many of the paintings appear to be those found in the Munich apartment last year.

Because of the complexity of the research, Berlin has dispatched experts in Nazi-era looted and banned art to assist a sole art historian assigned by the Augsburg prosecutors in charge of the investigation to catalogue the works.