One of street artist Banksy's best-known non-street works, a painting of chimpanzees debating in the British parliament, has sold at auction for more than STG9.8 million ($A18 million) in London.
Auctioneers Sotheby's had estimated the selling price of Banksy's 2009 oil painting Devolved Parliament at STG1.5 million to STG2 million.
But after a 13-minute bidding battle, the work went for a hammer price of STG8.5 million pounds, for a total of STG9,879,500, including fees.
The satirical work was first known as Question Time, after the weekly prime minister's questions in the British parliament, and renamed following minor alterations by the artist.
"Record price for a Banksy painting set at auction tonight," the artist wrote on Instagram as he posted a quote critical of expensive art. "Shame I didn't still own it."
The painting was exhibited in March at Bristol Museum, in the secretive Banksy's reported home city, to mark the date that Britain had been scheduled to leave the European Union.
"I made this 10 years ago. Bristol museum have just put it back on display to mark Brexit day," Banksy wrote on his Instagram account in March, adding the quotation: "Laugh now, but one day no one will be in charge."
Sotheby's noted that the work was offered at auction "exactly a year on from the unprecedented media storm surrounding the first ever creation of an artwork during a live sale".
It was referring to the auto-destruction of Banksy's Girl with Balloon, now known as Love is in the Bin, as the gavel came down to seal the final bid of STG1.04 million at a Sotheby's auction in Ocotber 2018.
The work, depicting a young girl with her hand extended toward a red heart-shaped balloon carried away by the wind, was partially shredded during the auction through a mechanical device hidden in the frame by the artist.
Sotheby's said Banksy, whose identity remains a mystery, had staged an "artist-driven hoax at the auction house's expense that epitomises [his] anarchic and rebellious spirit".
Australian Associated Press
