The authentication by French and Italian scientists also proves a mummified head of 16th century King Henri IV, used to compare DNA, is also genuine, the French television channel France 24 reported Monday.
Louis XVI, France's last monarch, was executed by guillotine on Jan. 21, 1793, the first victim of the "Reign of Terror," which followed France's revolutionary uprising.
It was customary to dip handkerchiefs into the blood of the victim at public executions to use as keepsakes, and the handkerchief in question was kept in a calabash, a form of squash used as a bottle, with the inscription "On January 21 Maximilien Bourdaloue dipped his handkerchief in the blood of Louis XVI after his decapitation."
The artifact had been in the possession of an Italian family for more than a century, but its definitive authenticity could not be resolved until it was compared with DNA from Louis XVI's ancestor, Henri IV, whose mummified skull had been in private collections, France 24 said.
Notable deaths of 2014 [PHOTOS]