MILAN, Jan 12 (Reuters) - Italy' biggest private broadcaster Mediaset accounted for 13.3 percent of revenues in the country's communications sector in 2015, industry regulator AGCOM said on Thursday.
The regulator will take into account the revenue share of Mediaset when it comes to investigate whether Mediaset shareholder Vivendi is in contravention of competition rules.
Italian regulations prevent companies from having an excessive share in both the domestic telecommunications and media markets.
The French media giant, which is already the main shareholder in phone incumbent Telecom Italia with a 24.9 percent share, has become Mediaset's second-largest shareholder with a 28.8 percent stake.
AGCOM opened a probe into the French media giant after aggressive stake-building in Mediaset in December, aggravating an ongoing spat with the Milan-based TV group over a failed pay-TV deal. (Reporting by Giulia Segreti, editing by Stephen Jewkes)