A painting by US pop artist Roy Lichtenstein has been slashed by a woman wielding a knife at an exhibition in Austria.
Roy Lichtenstein died in 1997
Nudes in Mirror - which was insured for $6m (£3.2m) - was damaged but not destroyed in the incident.
Police said a 35-year-old woman, from Munich, in Germany, pulled a knife from her bag and slashed it four times on Saturday afternoon.
She was stopped by visitors and staff at the Kunsthaus Bregenz museum.
Police spokesman Thomas Prodinger said her bag also contained a can of red spray paint and a screwdriver.
She faces charges of causing grave property damage - a crime that carries a punishment of up to five years in prison.
The woman said she slashed the painting because she believed it was a forgery - a claim denied by the exhibition's curator, Rudolf Sagmeister.
Mr Sagmeister, who organised the exhibition called Roy Lichtenstein: Classic of the New, said the painting could be restored.
Each cut measured about 30cm.
The exhibition, which opened in June, was due to close Sunday.
It features 41 works created from 1961 to 1995 by the pop artist, who died in 1997.
Lichtenstein was at the forefront of the 1960s pop art movement - along with Andy Warhol - which brought popular culture into fine art.