A painting smuggled into Tate Britain by graffiti artist Banksy went unnoticed until it crashed to the floor hours later.
Banksy stuck the painting to the wall of Tate Britain
Banksy, best known for creating the sleeve of Blur's current album, glued the painting to the wall on Wednesday after visiting the gallery in disguise.
The picture consisted of a rural scene with an image of police tape stencilled on to it.
It has now been placed in the London gallery's lost property section.
The painting was accompanied by a card which read "Banksy 1975. Crimewatch UK Has Ruined The Countryside For All Of Us. 2003. Oil On Canvas".
It added: "The artist has found an unsigned oil painting and then stencilled police incident tape over the top.
"He argues that ruining the work in this way reflects how our nation has been vandalised by an obsession with crime and paedophilia."
A statement from Tate Britain said that a man "had left a personal possession in one of the galleries".
"Tate security discovered the item a short while later and it was removed. It is currently being held in lost property," it added.
The artist is now selling another version of the painting at London's Tom Tom gallery - together with a video of him hanging it on the wall of the Tate.
Banksy, who keeps his real identity a secret for fear of prosecution, has turned down four requests to do adverts for a footwear brand and his work is usually seen only on walls in cities across the world.
He painted the Queen as a chimpanzee during her Golden Jubilee and sprayed "Mind the crap" on the steps of the Tate Britain before the Turner Prize ceremony.
Earlier this year an exhibition in which he spray-painted grafitti on cows, sheep and pigs, was closed after the animals became "hot and distressed".