ROME, Aug 23 (Reuters) - Italy's economy ministry wants a single, independent ultra-fast broadband network independent of former phone monopoly Telecom Italia (TIM), granting equal access to all market players, a treasury source said on Sunday.

The state would keep a strong role in the new company, the source added.

The Italian government is trying to negotiate a deal between phone group TIM and Open Fiber, which is jointly owned by state lender CDP and utility Enel, to merge assets and create a single national champion, with TIM reluctant to accept less than 50% of any network.

The Treasury source said the ministry was open to the participation of qualified institutional investors in the new network unit.

Earlier this month, TIM postponed to Aug. 31 a decision on the sale of a minority stake in its last-mile grid to U.S. investment firm KKR. (Reporting by Angelo Amante; Editing by Alex Richardson)