The National Gallery of Victoria is being asked to hand over a painting because it may have originally been looted by the Nazis.
Swiss lawyer Olaf Ossmann says the Head of a Man is a Van Gogh that once belonged to a wealthy Jewish industrialist, Richard Semmel, who lived in Berlin.
But the National Gallery of Victoria says that while the painting was once displayed as a $A20 million Van Gogh, tests have revealed that it was not in fact painted by the Dutch master.
Mr Ossmann says Semmel was forced to sell the painting when he fled the Nazis.
"Mr Semmel lost it, most of his collection, in auctions taking place in 1933 in Amsterdam," he told the ABC on Thursday.
The ABC reports Mr Semmel's heirs are believed to be two sisters living in South Africa, who are the grandchildren of a family friend who cared for Mr Semmel during his later years in New York.
The sisters have pursued a number of claims for work that once belonged to Mr Semmel, although not all have been upheld.
Mr Ossmann says they are determined to have the work returned.
"For them it's extremely important to restore their reputation and the history of the family," he said.
He says experts will now examine the history of the painting to determine its rightful owners.
"It is not a question about if it's a Van Gogh or not a Van Gogh," he said.
"It's definitely the painting from the former Semmel collection."
The NVG says it will follow due process in responding to Mr Ossmann's request and it is committed to honouring the principle of artwork confiscated or sold under duress due to Nazi occupation.
The ABC reports the authenticity of Head of a Man has long been questioned and the work was sent to experts at the Van Gogh Museum in Amsterdam for analysis in 2007. Tests there revealed the painting was not a Van Gogh.
At the time, the gallery said the finding did not mean that the painting was a forgery, but merely that it was by an unknown artist who may have been studying alongside Van Gogh in Paris in the 1880s.