A row over the authenticity of Andy Warhol artworks has engulfed the art world.
This original Warhol failed to sell
The Andy Warhol Authentication Board has decreed that only artworks the artist was directly involved in producing can be considered a Warhol original, according to reports in the Independent on Sunday and Sunday Telegraph in the UK.
Andy Warhol often left assistants to "mass produce" many of his most famous pictures, among them images of the Campbell soup tin.
The decision means many art collectors are left with Warhol works which are now considered copies and therefore worth much less, and some are threatening to sue the board.
About 15% of the artworks re-appraised by the board have had their authenticity rescinded, reports the newspapers.
The irony in the row is that Warhol himself questioned the idea of "original" art - choosing everyday items as subjects and producing thousands of prints of the same work.
Many of the prints of his most famous works were produced at his famous studio The Factory, often under his supervision.
But some works were printed from acetates of the originals by people Warhol had not even met, according to the Independent.
More than 20 art dealers and collectors are planning to sue the authentication board over the re-appraisals, reports the Sunday Telegraph.
The collectors believe the board are deliberately refusing to verify the works in an attempt to keep prices high, reports the Telegraph.
Film producer Joe Simon has had a number of works turned down, including a Warhol silkscreen self-portrait that he bought 14 years ago for $195,000.
Mr Simon said the board had withdrawn authentication for the work despite verifying it twice in the past.
"To my utter disbelief, my twice previously officially authenticated painting was returned to me denied, without any explanation. To this date they still refuse to give any reason."
Ron Spencer, a lawyer for the Authentication Board, said that its job was to determine the "intent" of the artist.
He told Vanity Fair magazine that even if a work were printed by a number of other people the board would still classify it as genuine.
"If Warhol conceived the idea and he then directed someone else to prepare a silkscreen, supervised the process of production and, in effect, signed off on it, as long as he said, 'That's good, that's what I wanted', Warhol created that work."
The board is creating a list of Warhol works to be included in a definitive catalogue.
Andy Warhol paintings are among the most prized 20th Century artworks.
A screenprint of Campbell's soup tin fetched £10m at an auction, while a Marilyn Monroe picture reached £11m at auction in 1998.