The French culture minister has demanded legal reform to ensure that activists who target artworks protected by glass are punished.
Rachida Dati spoke after an environmental activist stuck a poster on the glass case of Coquelicots (Poppy Field) by Claude Monet, the French impressionist, which hangs in Paris's Orsay Museum.
The action by Riposte Alimentaire, a French group that campaigns for a "social security system of sustainable food", was the latest in a string of attempts to use important artworks to gain publicity for its cause. The group threw soup on to the glass case of Mona Lisa in the Louvre in January.
A source at Orsay Museum said the 1873 work by Monet, which it describes as "one of the world's most famous paintings", was inspected, found to be undamaged and put back on display the same day.
Under French law, activists face up to seven years in prison and a fine of €100,000 for "destroying, damaging or deteriorating" a cultural item. But if there is no damage to the work, they often escape prosecution, according to lawyers.
A member of the French branch of Extinction Rebellion told Le Figaro this year: "The actions are not violent and they do not damage the artworks and so they are not criminally punishable."
Dati wants to change the law to ensure protesters no longer go unpunished in such cases.
"Once again, a cultural institution and an artwork have been targeted by iconoclasts," she said.
She said she had asked the justice ministry to implement "a criminal policy adapted to this new form of crime which attacks the most noble aspect of our cohesion — culture".
Officials in France and other European countries have struggled to deal with activists who target protected cultural items without causing damage. In the Netherlands, two Just Stop Oil campaigners received jail sentences for gluing themselves to the glass protection of Girl with the Pearl Earring, though this was later overturned. Similar protests have targeted historical documents including the Magna Carta.
