The 1937 painting, "Woman in Blue in Front of a Fireplace," has been the centerpiece of the Henie Onstad Art Center near Oslo since the museum was established in 1968 by shipping magnate Niels Onstad and his wife, Olympic figure-skating champion Sonja Henie.
The museum said in a statement Thursday that although it acquired the painting in good faith, it has "chosen to adhere to international conventions and return the painting to Rosenberg's heirs."
Norway is a signatory of the 1998 Washington Conference Principles on Nazi-Confiscated Art, which requires museums to review their collections for potentially looted works and when such a work is found, to try to locate rightful owners.
Now worth an estimated $20 million, the painting was taken by Goering after Rosenberg fled to New York in 1940, and sold to a Parisian art dealer later convicted of dealing in Nazi looted art. It was acquired from a different French gallery in 1950 by Onstad, who was apparently unaware of its provenance.
The museum investigated the painting's past only after being notified by the Rosenberg family of their claim to it in June 2012. The museum said that in the wake of the investigation — which it believes is the first of its kind undertaken in Norway — it has called upon the country's government to establish a committee to actually meet its obligations under the Washington Principles. Similar reviews have been launched in the U.S., Netherlands and Germany.
"Ultimately, it was the strength of the moral claim that persuaded the Henie Onstad Art Center to restitute this painting unconditionally to the Rosenberg heirs,' said Chris Marinello of Art Recovery Group, a lawyer representing the family.