The blaze broke out Monday at the Felix Nussbaum Museum in the western German city of Osnabrück, which has the world's largest collection of works by the Jewish painter.

No one was injured in the blaze, which destroyed about 10 square meters (108 square feet) of the wooden facade of the building. Investigators are treating the case as arson but said there was no indication it was politically motivated.

Firefighters found a burning pile of fabric next to the building.

"We can't yet say if the bundle of material was set alight intentionally or accidentally," a police spokesperson said, adding that the fire had caused thousands of euros worth of damage.

One theory was that a homeless person seeking shelter on the museum grounds might have set the blaze.

The building, which opened in 1998 as an extension of Osnabrück's Cultural History Museum, bears the jagged lines and maze-like design Libeskind later used in his landmark Jewish Museum in Berlin.

Nussbaum was born in Osnabrück in 1904 and became a leading painter and graphic artist in the 1920s and 1930s. After years spent in exile due to the rise of the Nazis in Germany, Nussbaum was arrested with his wife in Belgium, deported and killed at Auschwitz in 1944.