Following the alleged discovery of a Nazi treasure train in August, Poland has made headlines once again with claims that a Renaissance masterpiece was looted from Krakow during the 1939 occupation.

“The Fight Between Carnival and Lent” by Pieter Bruegel the Elder currently hangs in the Kunsthistorisches Museum in Vienna and is valued at an estimated €70 million (£50 million). The dispute over its provenance was sparked by the discovery of seventy-year-old documents in the archives of Krakow’s National Museum.

According to the museum’s director, Diana Blonska, the documents state that Charlotte von Wächter, wife of the city’s Nazi-era governor-general visited the museum in 1939 and removed the painting together with other works “which ended up in the antique markets of Vienna”.

A research paper prepared by Blonska also cites a letter written by the then-director of the museum, Feliks Kopera, to Krakow city authorities in March 1946, which reads:

“The Museum suffered major, irretrievable losses at the hands of the wife of the governor of the Kraków Distrikt, Frau Wächter, a Viennese woman aged about 35?.?.?.?Items that went missing included paintings such as: Breugel’s The Fight Between Lent and Carnival.”

Responding to the allegation, the Kunsthistorisches Museum in Vienna insists the painting removed by von Wächter is not the same painting which hangs in its galleries. It claims to have owned the painting since the 17th century.

Polish journalists were inspired to investigate the painting by University College London law professor Phillippe Sands who has written extensively on the Wächter family. Sands, who wrote the script for the film My Nazi Legacy told the Financial Times that a full investigation of the Bruegel provenance was needed. “There is evidence to suggest wrongdoing on a serious scale”.

The Polish deputy minister of culture has stated that Poland will ask Austrian authorities for a full investigation into the painting.

Meredith Hale, a fellow in Netherlandish art at Cambridge University has commented on the tremendous importance of this discovery: “If [the painting] was taken unlawfully from Krakow to Vienna it would be a huge story for the art world — as big as it gets”.

This latest controversy coincides with a wider campaign by Polish authorities to recover art and artefacts worth an estimated €22 billion, which were systematically plundered by the Nazis from Polish galleries and private collections during World War II.

What happens when you unwittingly buy a looted artefact?