Man disguised as granny arrested after smearing 'Mona Lisa' with cake

A screen grab of social media footage of the cake-smeared 'Mona Lisa' at the Louvre in Paris.

A 36-year-old man has been arrested and placed in psychiatric care after he smeared a glass screen encasing the Mona Lisa with cake, prosecutors said Monday, in a purported protest against artists not focusing enough on "the planet".

Officials at the Louvre Museum in Paris, where the enigmatic portrait holds pride of place, declined to comment on the bizarre incident on Sunday, which was captured on several phones and circulated widely on social media.