ROME Italy's antitrust authority opened an investigation into a broadband joint venture between Telecom Italia (TLIT.MI) and Swisscom (SCMN.S) unit Fastweb for possible violations of competition rules, it said in a statement on Thursday.
The two companies agreed in July to invest 1.2 billion euros (£1.02 billion) in a joint venture to speed up the roll-out of an ultrafast broadband network in 29 cities across Italy.
The authority said it had sent finance police to both companies on Thursday to acquire "elements needed for the investigation".
The joint venture "could reduce the intensity of competition" in the broadband and ultrafast broadband sectors, the statement said.
Telecom Italia and Fastweb both stood by the project and said they had behaved correctly. Fastweb said the joint venture was running fibre optic cables to 20,000 new homes each week.
Fastweb "is convinced both in the validity of the industrial project and in the correctness of its operations," the company said in a statement.
(Reporting by Steve Scherer and Gavin Jones, editing by Isla Binnie and Adrian Croft)