Two activists from the group Last Generation, which has called on the German government to take drastic action to protect the climate and stop using fossil fuels, approached Monet's "Les Meules'' at Potsdam's Barberini Museum and threw a thick substance over the painting and its gold frame.

The group later confirmed via a post on Twitter that the mixture was mashed potatoes. The two activists, both wearing orange high-visibility vests, also glued themselves to the wall below the painting.

"If it takes a painting - with #MashedPotatoes or #TomatoSoup thrown at it - to make society remember that the fossil fuel course is killing us all: Then we'll give you #MashedPotatoes on a painting!'' the group wrote on Twitter, along with a video of the incident.

In total, four people were involved in the incident, according to German news agency dpa.

A Barberini Museum spokesperson told dpa the museum had yet to determine whether the painting, part of Monet's "Haystacks'' series, . might have suffered long-term damage.

Police told dpa they had responded to the incident, but further information about arrests or charges was not immediately available.

The Monet painting is the latest artwork in a museum to be targeted by climate activists to draw attention to global warming.

The British group Just Stop Oil threw tomato soup at Vincent van Gogh's "Sunflowers'' in London's National Gallery earlier this month.

Just Stop Oil activists also glued themselves to the frame of an early copy of Leonardo da Vinci's "The Last Supper'' at London's Royal Academy of Arts, and to John Constable's "The Hay Wain'' in the National Gallery.