When is a Banksy not a Banksy?

LONDON (Reuters) - Cult graffiti artist Banksy, whose works can fetch hundreds of thousands of pounds and are popular with some of the world's biggest stars, has refused to authenticate five works up for auction this weekend in London.

Pest Control, the organisation tasked with authenticating the anonymous artist's works, said it would not approve any street pieces removed from their original setting, partly to crack down on fakes and partly to protect the original concept.

Banksy made a name for himself painting stencilled satirical and political images in public spaces, always keeping his identity hidden.

His work became so valuable that several street pieces were salvaged, including a painting attributed to Banksy on a wall in London that fetched 208,100 pounds in an online sale. The cost of removing the wall and replacing it was not included.

Ben Hanly of auctioneer Lyon & Turnbull said the sale would go ahead even without official verification, adding that there was no doubt the pieces on offer were original.

On its website, Pest Control said that since its creation in January, 89 street pieces and 137 screen prints attributed to Banksy have turned out to be false, potentially involving millions of pounds of losses for the buyers.

"Pest Control does not authenticate street pieces because Banksy prefers street work to remain in situ and building owners tend to become irate when their doors go missing because of a stencil," Pest Control said.

"He would encourage anyone wanting to purchase one of his images to do so with extreme caution, but does point out that many copies are superior in quality to the originals."

Hanly said the five works up for sale had been authenticated by the unauthorised organisation Vermin.