Dutch museums have at least 170 works of art in their collections which may have been stolen from their Jewish owners during World War II, according to research by the Dutch Museums Association.

In total 42 different museums, including the Rijksmuseum and the Stedelijk museum in Amsterdam appear to have stolen art in their collections, according to a list of all potentially stolen works identified to date.

Only the Rijksmuseum has not yet completed its investigation, Trouw said on Wednesday.

The probe into potential stolen art was started in 2009 when the Museums Association asked museums in the Netherlands to investigate the provenance of their collections after earlier research suggested just a few works of art were wrongly held.

Between 1933 and 1945 many Jewish collectors and dealers were forced to sell their works of art by the Nazi occupiers. Other paintings were simply confiscated or stolen and many ended up in museum collections after the war ended.

The most famous case of stolen art in the Netherlands is that of the Goudstikker collection, sold for a bargain price to the Nazi occupiers. In 2006, the collection was finally returned to the heirs of Jacques Goudstikker, a prominent Dutch art collector, who died while trying to reach exile ahead of the Nazi invasion.

Goudstikker left his collection in the hands of his staff, who sold the stock of at least 1,113 paintings for just 2.5 million guilders to German art dealer Alois Miedl and field marshall Hermann Goering. After the war, the paintings ended up at museums around the world. In 2006, the Dutch authorities agreed to return 202 pieces to Goudstikker’s heirs.

A number of sketches by Jan Toorop, thought to have come from the Goudstikker collection and now in the hands of the Gemeentemuseum in The Hague and the Stedelijk museum, are included on the website’s list of potentially stolen art.

The website states that the rightful owners or possible heirs of works of art with dubious provenance can present a claim to a special committee set up to assess claims.