(Recasts lead, adds source details, background)
MILAN, June 26 (Reuters) - Italy's Open Fiber is close to sealing a deal with utility Acea to use its infrastructure in Rome to roll out ultrafast broadband in the capital, two sources close to the matter said on Monday.
Open Fiber, the broadband business owned by Italy's biggest utility Enel and state lender CDP, has been seeking to do deals with utilities across Italy as it takes on rival phone group Telecom Italia in its network investments.
A deal with Acea -- which runs power, public lighting and water supplies in Rome -- would allow Open Fiber to cable up to some 1.5 million users, one of the sources said.
In April, a source said Telecom Italia had held talks with the Rome-based utility about using its infrastructure.
Telecom Italia, controlled by French media group Vivendi , has already been rolling out fiber optic infrastructure of its own but has opted to increase spending to upgrade its own network.
"Nothing has been signed yet between Acea and Open Fiber but they're not far off," one of the sources said.
Enel declined to comment.
Under European regulations, utilities are obliged to offer broadband operators access to their infrastructure on fair and reasonable terms.
Digging up roads to lay high-speed broadband can account for as much as 80 percent of deployment costs, the EU Commission has estimated. (Reporting by Stephen Jewkes; Editing by Keith Weir)