Germany said Wednesday experts had established a Camille Pissarro painting from the Cornelius Gurlitt art trove was looted by the Nazis and should be returned to the heirs of its rightful owners.

The oil painting from 1902 entitled "La Seine vue du Pont-Neuf, au fond le Louvre" (The Seine seen from the Pont Neuf) is "absolutely certain" to have been looted by Hitler's regime, the German culture ministry said.

"For the restitution, we are already in contact with the heiress of the former owner," Culture Minister Monika Gruetters said in a statement, without identifying the family.

Gurlitt, who died in May aged 81, had hoarded more than 1,000 paintings, drawings and sketches, including masterpieces by the likes of Picasso and Chagall, in his Munich flat for decades.

The Pissarro piece was discovered among more works uncovered at his Salzburg, Austria home.

The artworks were acquired by his powerful father Hildebrand Gurlitt who was tasked by the Nazis with selling artwork stolen from Jewish families in the 1930s and 1940s.

Research by a German government-appointed task force has already established that the artworks "Seated Woman" by Henri Matisse and "Two Riders on the Beach", painted by Max Liebermann, should be returned to the heirs of their rightful owners.

The Museum of Fine Arts in Bern, Switzerland, agreed in November to accept the controversial art trove left behind by Cornelius Gurlitt.

It agreed as part of an accord with the German government over the inheritance that it would return any works found to have been stolen by the Nazis.