The auction sum of the Impressionist work represents three times the estimated price of 550,000 British pounds, or $865,000. It was sold Wednesday evening (24.06.2015) in London for 1.865 million British pounds. The buyer has not been named.

Helena Newman, Sotheby's co-head of Impressionist and modern art, described the work as one of Liebermann's "finest portraits to appear at auction in over 20 years."

Also sold in Wednesday's auction was a Gustav Klimt portrait which had also been looted by the Nazis and subject to a restitution dispute. Its closing bid came in at 24.8 million British pounds, though it had been expected to sell for 18 million.

Liebermann's "Two Riders" from 1901 was put up for sale by New York-based lawyer David Toren, 90, who is one of several heirs. He acquired the work after a long restitution case. The piece had originally belonged to his great-uncle, David Freidmann, before it was plundered by the Nazis.

The Nazis then sold "Two Riders" to Hildebrand Gurlitt, known at the time as "Hitler's art dealer," and inherited by his son, Cornelius Gurlitt.

"Since then it has disappeared from public view," said Sotheby's director Bernhard Brandstaetter. "When it arrived here it was very dirty. You could see it had not been cared for. Many of the things Cornelius Gurlitt had in his house were just stuck somewhere, behind cupboards or under beds."

In a dramatic police raid in 2012, the piece was among 1,200 artworks found in Gurlitt's Munich residence which were suspected of having been looted by the Nazis. Since then, only two pieces, including the Liebermann, have been returned to their rightful owners.

"Two Riders" is the first of the Gurlitt collection to be auctioned off. The rest was willed to the Kunstmuseum Bern in Switzerland when Cornelius Gurlitt died in 2014 and is being examined by provenience experts to determined how many of the works had been misappropriated from their lawful owners.

kbm/eg (AFP, dpa)