The two paintings are a self-portrait of artist Joseph Kalter and his portrait of his wife Amalia Kalter.
During a ceremony in Warsaw on Monday, Piotr Gliński, Poland's minister of culture and national heritage, said the regained paintings were yet another example of successful efforts to recover artwork lost from Polish collections during the war.
However, the list of items that are still missing "is quite long,” he added.
It is estimated that some 516,000 artworks went missing from Poland during WWII, of which around 64,000 have been documented in a database kept by the Polish Ministry of Culture and National Heritage, according to Gliński.
The two missing watercolours appeared at an auction last year, and the auction house had no other choice but to hand them over for free to the Polish government because they are considered war losses under international law, officials said.
The watercolours by Kalter date to around 1811. Before WWII they were part of the Wrocław Museum of Handicraft and Antiquity, which operated from 1858 to 1945.
Radio Poland's Agnieszka Bielawska has the story.
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