The Uffizi Gallery in Florence has called on the German government to help return an 18th-century painting stolen by Nazi soldiers during the second world war.

Vase of Flowers, a still life by the Dutch master Jan van Huysum, is being held by a Germany family.

“Because of this affair, the wounds of the second world war and Nazi terror are not yet healed,” said Eike Schmidt, the museum’s director, who is German. “Germany has a moral duty to return the works to our museum and I hope this will be done as soon as possible, along with every other work of art looted by the Nazi army.”

The 47x35cm painting was originally put on display in Florence in 1824 after it was bought by Grande Duke Leopoldo II for his art collection.

It hung in the Pitti Palace until 1940, when it was moved to a nearby village after the outbreak of war. German soldiers seized the painting in 1944 as they retreated towards northern Italy after the Allied landings at Anzio and the liberation of Rome, and all trace of it was lost until 1991, shortly after German reunification.

Schmidt said that despite many requests by the Italian state, the German family that held the painting had failed to return it. He said several “intermediaries” had tried to sell the painting back, and the most recent “outrageous offer” had prompted the Florence prosecutor to open an investigation.

“The painting is already owned by the Italian state and therefore cannot be bought,” he said.

Schmidt posted on social media: “An appeal to Germany for 2019: We wish that the famous Vase of Flowers by Dutch painter Jan van Huysum that was stolen by Nazi soldiers be returned to the Uffizi Gallery.”

A photo of the painting was put up at the Pitti Palace on Tuesday accompanied by the word “stolen” in Italian, German and English.