Artworks deemed "degenerate" by the Nazi regime, unknown masterworks by the likes of Chagall and Matisse, and dozens of works thought lost in the war, are slowly being revealed by German authorities. Part of the trove of 1,406 artworks recovered from the Munich apartment of a reclusive, elderly man were made public on Tuesday.

Pablo Picasso, Pierre-Auguste Renoir, Henri Toulouse-Lautrec, Gustave Courbet, Oskar Kokoschka, Emil Nolde, are some of the masters represented in the Nazi-looted cache. There is also a 16th-century Durer, an 18th century Canaletto, a Courbet of a village girl, among the works out of public view for many decades.

Meike Hoffmann, an art expert at the Free University of Berlin who is examining the find, said, "The pictures are of extraordinary quality and are of huge scientific value. Many works were not known before."

The previously unknown artworks include an allegorical scene by Chagall, a rare self-portrait by Otto Dix, and a portrait of a woman by Matisse.

German authorities found 121 framed and 1,285 unframed works in the derelict apartment of 80-year-old Cornelius Gurlitt, the son of Nazi-era art dealer Hildebrand Gurlitt (d. 1956).

Gurlitt is under investigation for tax evasion and embezzlement, but he has not been charged with a crime.

Research is underway on 500 of the pictures, says Hoffman. Tracing provenance on the extensive trove will be difficult as some records may have been destroyed during wartime.