The Kremlin strongman and the disgraced billionaire reportedly cracked open a bottle of 1775 Spanish Jerez de la Frontera at the famed Massandra winery during a private visit by Berlusconi this month to the region Moscow annexed from Kiev in 2014.
The bottle was part of a legendary collection established by Prince Mikhail Vorontsov, who ran Crimea as governor-general in the first half of the 19th century.
Exiled Ukrainian prosecutors from Crimea said they are now investigating the alleged incident as a "seizure of government property".
"This wine is not just the property of Crimea or Massandra but of the whole Ukrainian people," Nazar Kholodnitsky, an official from the prosecutors' office, told AFP.
Kholodnitsky said that authorities estimated the bottle of wine could be worth "over USD 100,000".
Berlusconi met his long-standing friend Putin on a private visit to Crimea earlier this month that sparked ire in Kiev.
