For years, it has been widely accepted that artworks looted by the Nazis should be returned to their rightful owners. But now a prominent British expert has called for a stop to restitution -- and triggered protests in the art world.

The art connoisseur Sir Norman Rosenthal may be a British institution, but the equanimity often attributed to his compatriots is not one of his distinguishing features.

Rosenthal, the son of Jewish refugees from Germany and Slovakia, called for an end to the restitution of so-called Nazi looted art in an article in the journal The Art Newspaper.

The fact that someone who lost members of his own family in the Holocaust is now opposing restitution and is calling for an end to the practice has injected a provocatively dissonant note into an already angry debate -- and has triggered fierce protest. At issue is nothing less than the permanent whereabouts of some of the icons of art history.