By Elvira Pollina

MILAN (Reuters) -Telecom Italia (TIM) shares rose as much as 5% on Monday after Italian state investor CDP and Australian fund Macquarie submitted a joint bid for the former phone monopoly’s grid, rivalling an approach by U.S. firm KKR.

TIM is betting on a sale of its most prized asset to cut its 25 billion euros debt pile and fund an overhaul of the revenue-starved group.

Both offers value TIM’s grid, which is Italy’s main piece of telecoms infrastructure, in the region of 18 billion euros ($19.2 billion), sources familiar with the matter said.

The news is positive for TIM as a second approach increases its bargaining power,” broker Equita wrote in a research note.

The shares were up around 3.5% at 0.32 euros at 0900 GMT, levels not seen since last April.

The government of Prime Minister Giorgia Meloni has repeatedly said it wants to win control of TIM’s network while protecting jobs, but there is no common ground within the administration on how to reach that goal.

Regulation issues remain a hurdle for the new bidders, as CDP and Macquarie own TIM’smaller rival Open Fiber. CDP owns also a 10% stake in TIM.

In its approach for TIM’s grid, KKR, which already owns a minority stake in the former phone monopoly’s network, left the door open to involving a state-run entity, but it opposes CDP playing such a role due to antitrust issues.

Both bids are below the 31 billion euro price tag sought by TIM’s top investor Vivendi, whose support is key for any deal to go through.

Assessing KKR’s approach, which rises to 20 billion euros when including an earnout mechanism, TIM said last month the fund proposal “does not fully reflect” the value of its asset and added it would seek an improved offer by the end of this month.

($1 = 0.9398 euros)

(Reporting by Elvira Pollina; Additional reporting by Giancarlo Navach; Editing by Valentina Za and Keith Weir)