Jean-Luc Martinez, the Louvre president, was even more definitive. “The results of the historical and scientific study presented in this publication allow us to confirm the attribution of the work to Leonardo da Vinci,” he wrote in the preface. (His current term is set to end this month, and President Emmanuel Macron of France is overdue to announce whether he will extend Mr. Martinez’s tenure or appoint a new leader.)

The Louvre was so eager to include the “Salvator Mundi” in its anniversary exhibition that the curators planned to use an image of the painting for the front of its catalog, officials said.

But the Saudis’ insistence that the “Salvator Mundi” also be twinned with the “Mona Lisa” was asking too much, the French officials said.

Extraordinary security measures surrounding the “Mona Lisa” make the painting exceptionally difficult to move from its place on a special partition in the center of the Salle des États, a vast upstairs gallery. Placing a painting next to it would be impossible, the French officials argued.

Franck Riester, the French culture minister at the time, tried for weeks to mediate, proposing that as a compromise the “Salvator Mundi” could move close to the “Mona Lisa” after a period in the anniversary show, the French officials said. .

And even after the exhibition opened without the “Salvator Mundi,” in October 2019, French officials kept trying.

Prince Bader bin Farhan al-Saud, an old friend of Crown Prince Mohammed who had acted as his surrogate bidder for the “Salvator Mundi,” had later been named Saudi Arabia’s minister of culture. When he happened to visit to Paris, the French culture minister and Louvre president led him on a private tour of the museum and exhibition to try to persuade him to lend the painting, the French officials said.

A spokesman for the Saudi Embassy in Washington declined to comment.

A planned section of the catalog detailing the authentication was removed before publication, and the museum ordered that all copies of the report be locked away in storage.

Sophie Grange, a Louvre spokeswoman, said museum officials would be forbidden to discuss any such document because French rules prohibited disclosing any evaluation or authentication of works not shown in the museum.

Corinne Hershkovitch, a leading French art lawyer, said these “long-held traditions” had been “formalized by law in 2013, in a decree establishing the status of heritage conservators.”

But with the French refusing to talk about the painting and the Saudis refusing to show it, the proliferating questions about the painting have taken a toll, said Robert Simon, a New York art dealer involved in the rediscovery of the “Salvator Mundi.”

“It is soiled in a way,” he said, “because of all this unwarranted speculation.”

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