The Competition and Market Authority said it has launched six investigations into Google Drive, Apple's iCloud, and DropBox.
The investigation follows a number of complaints alleging unfair commercial practices by the tech giants.
"The parties involved are Google (for the Google Drive service), Apple (for the iCloud service) and Dropbox, each concerned both by a proceeding for alleged unfair commercial practices and / or violations of the Consumer Rights Directive and by one for alleged clauses vexatious included in the contractual conditions," the Italian watchdog said in a statement.
In particular, the investigations for unfair practices against Google and Apple concern the failure or inadequate indication, when presenting the service, of the collection and "use for commercial purposes of the data provided by the user and the possible undue influence in towards consumers".
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The same complaints were also raised against Dropbox. The companies were yet to issue a statement.
The investigation comes in the wake of a big action by the European Union against the tech companies to clarify their terms and conditions and provide greater privacy protections for the end-users. Facebook agreed to change its terms and conditions under pressure from EU officials last year.