Dozens more art works have emerged at the Austrian home of Cornelius Gurlitt, the German collector found in 2012 with hundreds of paintings believed stolen by the Nazis.
The latest finds in Salzburg include paintings by Renoir, Monet and Picasso.
A spokesman for Mr Gurlitt, who is in his 80s, said experts were examining the works to see if they were stolen during the Nazi era.
"After an initial assessment that suspicion is not confirmed," he said.
The spokesman, Stephan Holzinger, added that the paintings had been viewed on Monday.
More than 1,400 art works, estimated to be worth $1.35bn (£846m), were discovered in Mr Gurlitt's apartment in Munich in March 2012. But details of the find only came to light last year, apparently during a routine tax inspection.
Hundreds of the paintings were believed to have been looted by the Nazis. Mr Gurlitt's late father Hildebrand was an art dealer who sold paintings that had been confiscated or bought by the Nazis but kept many of the works himself.
A lawyer, Christoph Edel, who is acting as supervisor for Mr Gurlitt, has arranged for the works found at the collector's Salzburg home to be secured from any break-in or theft, German news agency DPA reports.
The state prosecutor in the German city of Augsburg who is handling the tax investigation in Munich had no comment to make on the latest revelations.
Officials in Austria told local media they had no knowledge of the case. "No warrant for a house search warrant has been ordered by us," a spokesman for the Salzburg public prosecutor told Austrian Press Agency.
The German authorities have been criticised for keeping the original discovery in Munich under wraps for more than 18 months.
Among the works found in 2012 were paintings either long thought lost or unknown, by Marc Chagall, Pablo Picasso, Henri Matisse, Otto Dix and Max Liebermann.
Mr Gurlitt, described as a recluse, told German website Spiegel last November that he had never done anything wrong and did not intend to give up the art collection, now in the hands of the German authorities.
His father had only ever bought paintings legally from museums and other art dealers, he insisted, and not from private individuals.