Still, experts are cautious about attributing the work to da Vinci.
Monna Vanna may be precursor to Mona Lisa.
Citing Conde Museum curator Mathieu Deldicque, the news agency AP reported that there are signs that it was painted by da Vinci himself. Leonardo's oil painting Mona Lisa also known as La Gioconda remains one of the world's most recognisable and valuable works of art. "It is nearly certainly a preparatory work for an oil painting", he added.
The Mona Lisa and Monna Vanna hold their hands in very similar ways, the right hand across the left and resting on the forearm, the fingers gently extended.
"At least both the Louvre's Mona Lisa and the naked Mona Lisa have one thing in common: They will always keep a lot of mysteries", Mr. Deldicque said.
Louvre conservation expert Bruno Mottin confirmed that the drawing dates from Leonardo's lifetime at the turn of the 15th century and that it was of a "very high quality".
But he told Le Parisien "we must remain prudent" about definitively attributing it to da Vinci, who died in France in 1519.
Art experts hope that they will be able to figure out the sketch's author before the Chantilly Museum holds an exhibition in 2019 to mark the 500th anniversary of Leonardo da Vinci's death.
More than 10 experts have been poring over the drawing for the past few weeks, using a variety of scans and other scientific methods. It's from the same period of the Mona Lisa, it's from the same region of Italy, and the technique is similar to the technique of the Mona Lisa.
But later specialists had their doubts and thought it more likely that it came from a member of the artist's studio.
There's something vaguely familiar about this charcoal sketch of a woman's face and nude torso - could it be an unclothed precursor to the Mona Lisa?