Hundreds of paintings, sculptures, and items of Judaica confiscated from European Jews by the Nazis may be illegally adorning the walls of Israel’s top museums, a group tasked with recovering assets lost in the Holocaust said Wednesday.

Hashava: The Company for Location and Restitution of Holocaust Victims’ Assets said it would team up with the Israeli museums thought to be in possession of Nazi-looted art — the Israel Museum, the Tel Aviv Museum of Art, the Ein Harod Museum, and the Ghetto Fighters’ House Museum — to track down the rightful heirs.

The artworks, seized during the war, were shipped to Israeli museums during the 1950s after having been located by various organizations in German museums or discovered in storage facilities by Allied military forces. However, no systematic search for the original owners has been undertaken until now.

“For the first time, the company [Hashava] will convene a historic discussion tomorrow, with the participation of representatives drafted to the efforts to locate the works of art stolen by the Nazis, in order to uncover and return the pieces to their legal owners,” said Israel Peleg, CEO of Hashava.

Hashava estimates that there are “hundreds” of pieces in Israeli museums, but Yoel Levy, an attorney and expert on Nazi-looted art told the Ynet news site that the precise number is difficult to approximate.

“We know how many pieces were stolen by the Nazis, but we don’t know about their distribution and therefore we are in a situation that is shrouded in uncertainty,” Levy said.

Israel is bound both by international and domestic law to actively seek to restore Nazi-confiscated assets to the owners or next of kin. The Israeli government signed accords on the subject at the 1998 Washington Conference on Holocaust Era Assets and the Terezin Declaration on Holocaust Era Assets in 2009, along with over 40 countries. In 2005, the Knesset passed “The Holocaust Victims’ Assets Law,” which calls for the identification of the owners of looted possessions.

Under the law, if the original owners cannot be found, the assets will be used for aid to Holocaust survivors or to advance educational projects and memorials. However, whether the Israeli museums will donate proceeds if the owners cannot be located remains unclear.