The Austrian culture ministry's art restitution council said that four of the works by the Austrian painter (1832-1839) had been bought by the Albertina gallery in 1939-40 and the two others after World War II.
Reichel, a renowned collector of Austrian art, died in Vienna in May 1943, four months after his wife Malvine Reichel had been deported to the Theresienstadt concentration camp.
She survived the war and was liberated by the Red Army in 1945. Their two sons fled in 1939 but the oldest was murdered by the Nazis in 1940.
Under a 1998 restitution law, Austria has returned some 10,000 Nazi-plundered paintings to the descendants of their former owners.
Most notorious was a painting by Gustav Klimt, a 1907 portrait of Adele Bloch-Bauer, which the Austrian state was forced to return to the heirs of its previous owner in 2006 after a lengthy legal battle.
A Klimt landscape stolen by the Nazis and returned this year to the family of the Jewish owner sold for a huge $40.4 million at Sotheby's in New York last month.http://acn.liveauctioneers.com/index.php/features/crime-and-litigation/6062-austrian-gallery-ordered-to-return-nazi-stolen-romako-works