Alex Branczik, head of contemporary art for Europe at Sotheby's, said the shredded painting was "the first artwork in history to have been created live during an auction."
Shredded artwork 'doubles' in value: experts
In the wake of Banksy's prank, several experts suggested that the shredded artwork could now be worth more than double its original price.
"Banksy might think that by destroying his art he's undermining capitalists who buy it, but he's wrong," said Mikael Faujour of the specialist French art magazine Artension. "The leftovers from this destruction will acquire a new prestige and additional monetary worth."
Thierry Ehrmann, who heads Artprice, a firm closely monitoring art market prices, claimed it could now be worth more than €2 million. "Banksy reminds people that, even in a prominent auction, all his art is fleeting," he said.
Some experts have even questioned whether Sotheby's conspired with the artist to pull off the prank. Auctions houses usually study both the painting and the frame with careful attention prior to sale, they say.
From spray painter to political artist
"Balloon Girl," which depicts a small child reach towards a heart-shaped balloon, was originally stenciled on a wall in east London.
dm/rc (Reuters, AFP, AP, dpa)