Auction house Sotheby's says it is working to resolve a dispute over the intended sale of a painting by Vincent van Gogh.
Châtaigniers en Fleurs, which carries an estimate of $180m (£136m), is due to go under the hammer in New York on Wednesday.
But representatives acting for heirs of the Fischer family - earlier German owners of the work - say it may have been sold under duress during the rise of the Nazis.
Sotheby's say its own "extensive research" has not established this, but say they will work with the family to try and reach a solution.
"Sotheby's takes provenance and restitution matters extremely seriously and has undertaken extensive research into the ownership history of Châtaigniers en fleurs," Sotheby's told the BBC in a statement.
"We are aware of the concerns recently raised by representatives of the Fischer heirs and have been in dialogue with them regarding the painting's history.
"While our research to date has not established that the painting was sold under duress, we recognize the importance of engaging thoughtfully and constructively with the family and are committed to working toward a mutually satisfactory resolution."
The painting - whose name translates as Blossoming Chestnut Trees - is being sold as part of a set called the Blaquier-Arrieta Collection.
