The pieces of art that were looted by the Nazis and later saved by the US military;s 'Monument Men' were never returned to their rightful Jewish owners at the end of the second world war, according to a report in Süddeutsche Zeitung newspaper.
The explosive findings claim that the pieces of art were eventually sold on by the Bavarian government at a profit, after they were handed over in 1949.
Some works were even allegedly sold to the families of convicted Nazi war criminals, throwing a dark shadow over the legacy of the Monuments Men, which were a small unit of art historians given the task of saving Europe's cultural heritage from destruction during the Second World War.
Serving on the front line alongside American troops, the group tracked down over 10,000 works of art, many of which had been looted from Jewish owners under one of the most oppressive political regimes in modern history.
When US forces withdrew from Germany in 1949, the works were handed over to the newly-formed Bavarian government.
The story has become the stuff of legend, even sparking a successful Hollywood film starring George Clooney and Matt Damon.
However, an investigation by the Commission for Looted Art in Europe has since found that many of the works have never been returned to their rightful owners.
One such piece is ‘Picture of a Dutch Square’, a 300-year-old copy of a painting by Dutch artist Jan van der Heyden that was looted from a Jewish collector in Vienna, never to be returned to their family.
It was instead sold to Henriette Hoffmann, the daughter of dictator Adolf Hitler's personal photographer and ex-wife of Baldur von Schirach, the Nazi governor of Vienna, who was later convicted of crimes against humanity at the Nuremberg trials.
Hoffman then sold the painting a few months down the line for an allegedly considerable profit to Xanten Cathedral, where it hangs today.
Margit Knom-Marcon, director of the Bavarian State Archive, told the newspaper that the issue needed to be addressed by the government.
“All governmental agencies are required by law to make their documents accessible. And the State Art Collection is a governmental agency," she added.
“But we do not have a single document from the State Art Collection’s archive.”
The issue is unlikely to go down well in the US, with the legend surrounding the real-life Monuments Men now in real danger of being eroded away.