The Salvator Mundi was described as "one of fewer than 20 known paintings by Leonardo" when it sold for a record $642 million in 2017, only to disappear without trace amid increasing doubts about its attribution to the Renaissance master.
Months after the Louvre Abu Dhabi suddenly cancelled its unveiling, the picture is now facing an apparent snub from the Louvre in Paris, which is understood to have scrapped plans to display it in its major Leonardo exhibition.
Jacques Franck, who has been a consultant to the Louvre on Leonardo restoration projects, told The Sunday Telegraph that politicians at the highest levels and Louvre staff "know that the Salvator Mundi isn't a Leonardo".
He is among those who believe that it was painted primarily by one of Leonardo's studio assistants, and has written to Emmanuel Macron, the French president, warning him against inaugurating the Louvre's autumn Leonardo exhibition if the Salvator Mundi, a depiction of Christ as the "Saviour of the World", is included. He has told him that it would be "almost scandalous".
He added: "The Louvre is the dominant museum collector of Leonardo in the world. They have the Mona Lisa, Saint Anne, Saint John the Baptist, the authentic version of The Virgin of the Rocks, and plenty of drawings.
"It would be a shame to have a 'workshop Leonardo' next to the Mona Lisa. I wrote to Macron not to inaugurate the exhibition if it were to be so. A lot of politicians have told me, it must be stopped.
"Macron cannot compromise himself inaugurating an exhibition where not-a-real Leonardo would be next to the Mona Lisa, presented as a beautiful masterpiece... Unthinkable."
He said that politicians within the Ministry of Culture and those closest to the President are concerned about the potential embarrassment: "A Louvre insider told me, 'I hope that horror won't be in the Louvre - ever'."
Its Louvre display has been assumed since its director, Jean-Luc Martinez, told a French radio station, shortly after the auction, that he hoped to secure the work for his Leonardo exhibition.
Mystery surrounds the painting's whereabouts. The National Gallery unveiled it in its Leonardo exhibition in 2011, where it received support from some of the world's foremost scholars, breaking auction records at Christie's in New York in 2017.
After weeks of speculation about the buyer, with reports suggesting that it was Saudi Crown Prince Mohammed bin Salman, Christie's confirmed that the Abu Dhabi Department of Culture and Tourism "is acquiring" the painting. Its September unveiling at the Louvre Abu Dhabi was cancelled without explanation.
Questions have also been raised about its extensive restoration. In December 2017, photographic evidence revealed that its appearance had changed between its unveiling in 2011 and its auction in 2017.
Extensive research by Michael Daley, director of ArtWatch UK, has further challenged the picture's provenance. Hearing that the Louvre was now unlikely to exhibit it, he said: "This is an extraordinary development... What we now have is effectively an undead painting - no one believes in it; no one will say where it is; no one can lay it to rest."
2005 Acquired for less than $14,566 from a New Orleans estate sale by a pair of art dealers.
2008 After extensive restoration, the dealers conclude the painting is a missing Da Vinci, authenticated by leading experts.
2011 - Unveiled at Leonardo exhibition at National Gallery in Washington DC
2017 - Sells for a record $642 million at Christie's in New York. Buyer is later revealed to be Abu Dhabi's Department of Culture and Tourism.
December 2017 - Photographic evidence reveals appearance has changed between 2011 exhibition and New York sale.
September 2018 - Unveiling at Louvre Abu Dhabi cancelled without explanation
February 2019 - Louvre in Paris is understood to have pulled it from autumn Leonardo exhibition.