Since it launched in late 2011, Fine Arts Auction Miami has operated fairly quietly in Miami’s Wynwood neighborhood, holding regular auctions without stirring up much attention. Until now.

The auction house based on the ground floor of an art storage facility has sparked an international firestorm with the planned sale of a mural by the British street artist Banksy that was torn from the exterior of a North London building.

Depicting a barefoot boy kneeling at a sewing machine to produce a string of United Kingdom flags, “Slave Labor (Bunting Boy)” has an estimated value of $500,000-$700,000. It measures four feet high by five feet wide. The image is the cover for the Feb. 23 auction’s catalog.

Not long ago, the mural graced the outside of a Poundland shop — think dollar store, but in British pounds — in the Wood Green neighborhood of London. It disappeared over the weekend, according to reports in London newspapers, leaving a gash in the wall and plenty of anger across the pond.

Alan Strickland, a local council representative for the London borough of Haringey, told the Daily Mail that residents were “shocked” at the disappearance of the mural that had given them so much pride.

“The community feels that this art was given to us, for free, and it’s now been taken away to be sold for huge profit,” he told the British paper. “I’m very angry about the Banksy going — we want our Banksy back!”

It was unclear who removed the work. A representative for Poundland wrote on Twitter: “We would like to confirm that we are not responsible for either selling or removing the Banksy mural. We are currently investigating.”

Frederic Thut, who established the Miami auction house, was working Tuesday in his office on the ground floor of Museo Vault, on Northwest 29th Street east of Interstate 95. But an employee at the storefront closed Thut’s office door when a Miami Herald reporter showed up and said he wouldn’t say anything beyond the statement the company had put out.

That statement says: “FAAM has done all the necessary due diligence about the ownership of the work. Unfortunately we are not able to provide you with any information by law and contract about any details of this consignment. We are more than happy to do that if you can prove that the works were acquired and removed illegal [sic].”

Earlier, Thut told the British newspaper The Sun that the piece along with another mural, Wet Dog, were being offered by a “well-known collector” who was not British and who had signed a contract saying that “everything was above board.” The estimate for Wet Dog, which measures 79 by 63 inches, is $600,000-$800,000.

The Wet Dog mural, painted in the Palestinian city of Bethlehem in 2007, was shown by Southampton, N.Y., gallery owner Stephan Keszler as part of “Banksy: Out of CONTEXT” at the CONTEXT Art Miami show in December. The piece was not for sale during the show, but Keszler tried unsuccessfully to sell it and others in 2011. None sold after Banksy, whose identity has remained a mystery, released a statement criticizing the gallery owner and suggesting the works were not authentic.

The Miami Herald emailed Keszler with questions about this weekend’s auction, but he did not answer any of them. “I am replying to your request out of courtesy but I am not able to provide you with more details,” said the reply email, which was signed “Stephan.”