GERMANY — The Conference on Jewish Material Claims Against Germany (Claims Conference) has accused Germany of being morally complicit in the theft of 1,500 works of art discovered in a Munich apartment owned by the son of a war-time art dealer.

The collection, which includes works by Matisse and Picasso, was discovered at the home of Cornelius Gurlitt and could be worth more than $1.35 billion, a report by German news magazine Focus said.

Gurlitt’s father was an art collector during the Nazi regime tasked with removing “degenerate” art from display around the country. The Claims Conference says the works were forcibly seized or extorted from Jewish art collectors.

“We demand the paintings be returned to their original owners. It cannot be, as in this case, that what amounts morally to the concealment of stolen goods continues,” said Claims Conference representative Ruediger Mahlo, Reuters reported.