An Israeli group focused on Holocaust restitution says hundreds of works currently hanging in Israeli museums may have been the products of Nazi looting.

Hashava, The Company for Location and Restitution of Holocaust Victims’ Assets, made the allegation ahead of a meeting Thursday with the Israel Museum, which said it strictly rejects the idea that any of its art might have been seized from Jewish victims in World War II.

“Thanks to the different processes undertaken by the Israel Museum, many art works have been returned to their owners since the year 2000,” read a statement from the Israel Museum.

However, Hashava argued the Jewish state has not done enough in the area of returning Nazi-looted pieces to Holocaust survivors and their descendants, which has seen a large movement in Europe.

“While other countries are making active efforts and are investing their money–including publishing databases and research, implementing registration, locating and cataloging information in archives, conducting campaigns to locate the owners–in Israel no systematic and adequate effort is actually being carried out by the museums to locate the owners and their heirs of the artworks,” the group said in a statement.

Hashava added that many works stolen by the Nazis and uncovered by Allied forces were sent to Israel after the war, landing in the hands of officials, not original owners.