MILAN, June 3 (Reuters) - Italian telecommunications firm Open Fiber is nearing a preliminary deal to secure some 2 billion euros ($2.2 billion) in extra funds from its lenders and shareholders following months of complex talks, three sources said on Monday.

The funding is vital to shore up the finances of the telecoms firm and to help the wholesale-only network operator to complete its fast broadband rollout plans.

After months of negotiations, Open Fiber shareholders - state lender CDP and Australian fund Macquarie - agreed to share the burden almost equally with the company's lenders, according to sources.

That means CDP and Macquarie are jointly going to inject some 1 billion euros to beef up Open Fiber's finances, while banks will provide an almost equal amount in new financing due in 2029.

Negotiations with lenders are progressing and a preliminary deal could be clinched as early as this week, the people said.

As part of ongoing talks with banks, Open Fiber has already secured the unblocking of 800 million euros which form part of a 7.2 billion euros financing package provided by a pool of over 30 Italian and international lenders and which the company was forced to renegotiate after missing some performance targets, the people added.

Open Fiber was created in late 2015 to try to address Italy's delays in upgrading the country's broadband infrastructure to full fibre, especially in the most remote areas of the country.

State lender CDP owns a 60% stake in the operator and Australian fund Macquarie holds the remaining 40%.

Open Fiber's network assets are ultimately expected to be combined with those of former phone monopoly Telecom Italia (TIM) which has agreed to sell its fixed line network to U.S. fund KKR, a deal backed by the Italian government. ($1 = 0.9222 euros) (Reporting by Elvira Pollina Editing by Keith Weir)