Using multispectrum imaging, Maurizio Seracini found the brown monochrome painting on top of da Vinci's under-drawings was carried out by a minor artist about 20 years after da Vinci had finished and abandoned the preparatory work, The Times of London reported.
The presence of da Vinci's own under-drawings have already been recreated from the work, showing knights at battle, an elephant and workers rebuilding a ruined temple.
Da Vinci was commissioned to do the Renaissance work by a community of monks in Scopeto, near Florence, in 1481, and historians agree the monks were probably shocked when they saw the work being developed by the 29-year-old artist.
"They almost certainly didn't want a bloody battle going on a few inches from the Madonna's head," Seracini said.
A video of Seracini's findings is available online at florence.tv.