Switzerland's highest court has rejected Italy's request for the return of an oil painting attributed by some to Leonardo Da Vinci, ruling no Swiss laws were broken when the work was brought over the border.

Titled "Portrait of Isabella d'Este" and dated to the 16th century, the painting became the subject of an international tug-of-war after an Italian woman, Emidia Cecchini, sought to sell it in 2013.

Police were alerted to its existence when an Italian lawyer surfaced with a mandate to sell it for no less than €95 million ($106 million). Art experts have yet to agree on whether it really is by the Renaissance master.