James Beck, Professor of Art History at Columbia University in New York, believes that Duccio’s Madonna and Child, which the Met dates to 1300, is the work of a much later hand. He says that it could never have come from the hand of a towering genius considered, with Giotto, to have been a principal founder of Western European painting.

“It is a fake based upon indications found in works by or associated with Duccio,” he said. “It is not even a good forgery.”

Barely a dozen of Duccio’s works survive. They include his Maestà (Madonna with Angels and Saints) altarpiece, which dates from 1308-11, in the museum of Siena Cathedral; it is considered a milestone of Western art.

Professor Beck pointed to the “low quality” of the Met’s painting — notably the Child’s raised arm and hand, “which appears like a stump”, and its “gourd-like head, which is quite at odds with confirmed and documented paintings by Duccio”.

That the painting shows the Madonna and Child behind a parapet is the most compelling proof that the painting “cannot be genuine”, he believes, dismissing the claim by Keith Christiansen, the Met’s curator, that it is “the first illusionistic parapet in European art”.

Professor Beck said: “We are asked to believe that the modest little picture represents a leap into the future of Western painting by establishing a plane in front of Mary and the Child. This feature, a characteristic of Renaissance not Medieval pictures, occurs only a hundred years after the presumptive date of the picture . . .

“Devastating to the Met’s claims is the fact that no other examples with the combination of elements — Madonna and Child with a space-defining parapet — are found among the confirmed works by Duccio or his followers, or in all of Tuscany, for that matter.”

Whoever produced the painting, Professor Beck suggested, knew the Renaissance system of depicting space and planes. “The artist or forger must have worked up this idea from hindsight rather than foresight.”

In September he will be publishing his conclusions in a book, The Crisis of Connoisseurship: from Duccio to Raphael.

Mr Christiansen said that leading scholars had confirmed the attribution and that Professor Beck was wrong. “What everyone else sees as a sign of quality and innovation, he sees as weakness. There is no reason to doubt the period and authenticity of the picture.”

Professor Beck has never been afraid to voice his opinion. As president of ArtWatch International, which campaigns for the welfare of works of art, he has also dismissed The Madonna of the Pinks, the £35 million Raphael at the National Gallery, as a copy.

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