(Recasts with Enel statement) Infrastructure fund Macquarie has...

(Recasts with Enel statement)

Infrastructure fund Macquarie has made an offer to buy all or part of Enel's ENEI.MI 50% stake in Italy's Open Fiber broadband network operator, the Italian utility said on Tuesday.

Open Fiber is a wholesale-only broadband operator jointly owned by Italian utility Enel and state lender Cassa Depositi e Prestiti (CDP).

Enel said in a statement that its board had received a non-binding bid from Macquarie Infrastructure Real Asset on June 10 for "the acquisition of the whole or part of the stake".

It added it would wait for any updates on the offer. The statement confirmed what two sources had told Reuters earlier, after Italian daily la Repubblica reported that the Australian fund had made an offer "hard for Enel's chief executive not to submit to the board".

The report did not say how much Macquarie had offered but added that Open Fiber was estimated to be worth between 3 billion and 6 billion euros ($6.8 billion).

Macquarie declined to comment. "Macquarie illustrated its offer to some key government representatives, though no talks have actually been held with the Treasury," an Italian government source said.

Rome sees building ultra-fast broadband as a priority and has called on former phone monopoly Telecom Italia (TIM) TLIT.MI and Open Fiber to reach an accord quickly on a single network.

TIM has been in talks for months over a merger of its fibre network assets with those of Open Fiber but differences over issues like governance and regulation have thwarted efforts.

TIM, itself partly owned by CDP, has its own retail arm, while Open Fiber is a wholesale-only venture that offers different operators access under the same conditions.

It is in exclusive talks with U.S. infrastructure fund KKR to invest in its own secondary last-mile network.

Sources told Reuters recently that Macquarie was interested in buying a stake in Italian motorway group Autostrade per l'Italia and would be ready to team up with CDP. ($1 = 0.8837 euros)