BANKSY could be prosecuted for shredding his own Girl With Balloon artwork after it sold for £1million at a Sotheby’s auction, a legal expert claims.

Salomé Verrell, a solicitor and senior lecturer at the University of Law, said the graffiti artist “committed criminal damage” because the auctioneer’s hammer had already come down.

The Girl With Balloon was due to go to the new owner, but instead it was fed through a shredder that Banksy revealed he hid into the frame meaning the artist technically destroyed someone else's property.

Verrell says Bansky broke the law with the stunt and if police can figure out who he is then he should expect police to turn up at his door.

She said: “When Banksy shredded the painting, he was damaging someone else's property, and he did so intentionally and knowing that it belonged to someone else.

"It seems Banksy is not content with alleged criminal damage of buildings but now has apparently criminally damaged someone else's painting.

"The painting belonged to the highest bidder because the hammer had gone down and the sale had ended before the shredding began.

"Therefore at the time of shredding, the painting belonged to someone other than Banksy and he knew that since he was selling it at auction.

"He intended to destroy it knowing it belonged to someone else.”

She said that it falls under the Sale of Goods Act of 1979 and the Criminal Damage Act of 1971.

Under the Sales of Goods Act, the artwork had transferred owners as soon as the gavel fell.

Verrell said that even though the woman who bought the painting was happy with the result it would be interesting to see if she didn’t want to artwork in the end.

She added: "It could however be said that he actually improved (or increased the value) of the piece, and that (unknown to the buyer) it was a dynamic and evolving piece of art.

"Damage is a matter of fact and degree in each case.

"If the piece itself is damaged by shredding this does seem to fit the definition of 'damage' within the Act, but the increase in value may throw this into doubt.

"However, just like his antics when spray painting someone's exterior walls, without a loser, that is, someone to make a complaint to the authorities, it seems Banksy will continue to get away with breaking the law, in the name of art.”

The Sun Online approached Banksy's representatives for comment.