Berlin – An expert panel has been asked by the German foundation to rule whether its painting by Spanish artist Juan Gris was looted by the Nazis.

The state-run Kunstsammlung Nordrhein-Westfalen said Tuesday that its research doesn’t support claims by the heirs of Jewish collector Alfred Flechtheim that the picture belonged to him when it was sold in London in 1934.

Nevertheless, the foundation has asked the Limbach Commission to determine the rightful owner of Gris’ painting “Violin and Ink Bottle on a Table,” which it bought in 1964.

The issue of restitution for Nazi-looted art has returned to the fore in Germany since the revelation last year that collector Cornelius Gurlitt had hoarded hundreds of valuable paintings at his home, some of which had been taken from Jewish owners before World War II.