FRANKFURT, Germany — German customs officials discovered about 1,500 works by modern artists including Pablo Picasso, Max Beckmann, and Marc Chagall that were confiscated by the Nazis and long deemed to be lost, Focus magazine reported, without saying how it obtained the information.

The art works, estimated to be worth 1 billion euros ($1.35 billion), were found in an apartment in Munich after a random check on an elderly man traveling from Switzerland to Munich by authorities cracking down on money-laundering prompted further investigation, according to the German magazine. The raid took place in secret two years ago, it said.

The man, named as Cornelius Gurlitt, is the son of a Munich art dealer who purchased the works in the 1930s and 1940s, Focus said.

The paintings, sketches and prints, found buried among cans of food and rubbish, include a work entitled Portrait of a Lady by Henri Matisse that once belonged to Jewish art collector Paul Rosenberg, it said.

Rosenberg, whose granddaughter is Anne Sinclair, the estranged wife of former International Monetary Fund Managing Director Dominique Strauss-Kahn, was forced to leave his collection behind when he fled the Nazis, Focus said.

Gurlitt kept the artworks and is believed to have sold some as a source of income over the years, the magazine reported.

Works by Emil Nolde, Franz Marc, Paul Klee, Oskar Kokoschka, Ernst Ludwig Kirchner, Max Liebermann, and Albrecht Duerer were also discovered in the raid, it said.