The country's postal police, which handles cases related to the Internet, is investigating the matter, the source said.

Magistrates in Italy can open an investigation without identifying a suspect or specifying a crime. The judicial source said the investigation would look into whether Facebook data was used by third parties to influence Italian elections.

Facebook has lost more than $50 billion in market value since allegations this week that Cambridge Analytica improperly accessed data to build profiles on American voters and influence the 2016 U.S. presidential election.

(Reporting by Domenico Lusi; Writing by Isla Binnie; Editing by Crispian Balmer)