Following an intensive survey, Dutch museums have identified 139 artworks in their collections — including paintings by French master Henri Matisse and Dutch impressionist Isaac Israels — that have dubious provenance and were likely snatched forcibly from Jewish owners during the Nazi regime.

The €1.3 million ($1.87 million Cdn) review, which began in 2009, looked specifically at art acquired by hundreds of institutions after 1933.

Experts searched specifically for art with gaps in ownership records during the 1930s and 1940s, when the Nazis spread across Europe and forced Jewish collectors to sell their artwork or simply plundered items outright.

"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.

Returning them is "both a moral obligation and one that we have taken upon ourselves."

As part of the lengthy survey, the museums have also launched a Dutch website that lists the artworks of potentially questionable origin and will help assist prospective heirs to make restitution claims. An English translation of the site will launch in 2014.

In the 1950s, the Dutch government restored some Nazi-looted artworks to their rightful owners, but others remained the property of the state.

Dutch museums undertook a review years ago, but had focused only on works acquired between 1940 and 1948. Officials were prompted to take a look even further back upon learning of specific auctions that took place before the Second World War.

"We know that there were doubtful transactions concerning works acquired before 1940, after Kristallnacht," Weide said.

Kristallnacht, the Night of the Broken Glass, took place on Nov. 9, 1938, and was a night of co-ordinated, Nazi-incited riots in Austria and Germany that marked the beginning of the regime's systematic campaign to destroy the Jewish people in Europe.

Over the past decade, museums worldwide have slowly opened up to returning Nazi-looted art to rightful heirs. However, when the disputed artworks are in private hands and come up for auction, heirs must often resort to legal claims and mediation with current owners for their return — attempts which have been moderately successful.

On Tuesday, officials at the Canadian Embassy in Berlin unveiled a Nazi-looted 19th century artwork — the 1837 painting Scandinavian Landscape by Andreas Achenbach — that was recently recovered with the help of Cologne auction house Van Ham Fine Art Auctions.

It had been owned by famed Montreal art collector Max Stern, a German Jewish art dealer who was forced to sell or relinquish hundreds of artworks in the late 1930s by the Nazis. He did not receive the proceeds from the sales and eventually fled Germany, ultimately settling in Canada.

With files from The Associated Press