The detailed rendition of the male physique corresponds to Michelangelo sketches found in the Louvre.
The way in which Mary’s clothes tumble to the ground in lavish folds is “typically Michelangelo-esque,” said Prof Claudio Crescentini, an art historian who has written a new book on the project, Michelangelo and the terracotta Pietà.
The team’s findings were reviewed by an independent art historian and museum curator, Patrizia Nitti.
“In all honesty, I had many doubts to begin with. It’s very often that people come to us claiming they have found a work by Michelangelo. We are very, very careful and sceptical,” said Ms Nizzi, the former director of the Musée Maillol in Paris.
But having studied the documentation, she now believes the figurine is by Michelangelo. “It’s a wonderful gift to the Italian people,” she said.
The historians’ claims were favourably received by L’Osservatore Romano, the Vatican’s newspaper.
“The terracotta served as a model for the 22-year-old Michelangelo for the funeral monument commissioned by the French cardinal Jean de Bilhères de Lagraulas, who wanted to leave a spiritual legacy to French Catholics,” the newspaper wrote in a lengthy review.
The statuette remains in private hands but has already gone on display in Paris, where it was viewed by 200,000 visitors.