"An international interconnection problem impacting the service at the national level was detected. Analyses are underway to resolve the problem," a Telecom Italia (TIM) spokesperson said.
Italy's ANSA News agency reported there are no signs yet that hackers were responsible for the widespread outage.
Network data from NetBlocks shows widespread disruption to internet service across Italy on Sunday. It's been reported that the telecommunications blackout might stem from leading operator Telecom Italia.
NetBlocks' real-time network data shows that national connectivity plunged from around 100% to 26% this morning.