Dutch museums have found 139 artworks that may have been looted during the Nazi era, including paintings from masters such as Matisse, Klee and Kandinsky.
The major review of all museum collections in the country found art that had either dubious or definitely suspect origins.
"These objects are either thought or known to have been looted, confiscated or sold under duress," said Siebe Weide, director of the Netherlands Museums Association. He said returning them is "both a moral obligation and one that we have taken upon ourselves."
The review also listed the names of 20 people whom the museums said definitely had 61 pieces of art taken from them. The museums said they were getting in contact with or seeking their heirs, including the heirs of Jewish art dealer Albert Stern, the dead owner of the Matisse.
The museum purchased the painting from Lieuwe Bangma family in 1941, but Mr Stern was its owner before the war and the Bangma family is known to have given shelter to his granddaughter during the war.
A previous Dutch review that concluded in 2006 focused on art obtained during the Second World War. This time all Dutch museums reviewed the chain of possession for all their artwork created any time before the end of the war in 1945, with a special focus on detecting pieces that had any gap in their ownership record after the Nazis came to power in Germany in 1933.
American and British museums have already conducted investigations similar to the Dutch one. In Germany and many other countries, similar investigations are still underway.
Among the objects found were 69 paintings, including French painter Henri Matisse's 1921 "Odalisque"painting of a half-nude reclining woman at Amsterdam's Stedelijk museum, one of the country's top tourist draws.
Other paintings included works by old Dutch masters such as Jacob Gerkitsz Cuyp, Impressionist Isaac Israels and modernists Paul Klee and Wassily Kandinsky. Other objects uncovered in the investigation included drawings, sculptures, antiquities and Jewish ceremonial objects.