MILAN, Nov 22 (Reuters) - Shares in Telecom Italia were indicated up 30% on Monday, after U.S. fund KKR presented a non-binding proposal to buy Italy's former phone monopolist valuing it at 10.8 billion euros ($12 billion).

The size of the move prevented shares in Telecom Italia (TIM) to start trading.

Telecom Italia's (TIM) net debt of 22.5 billion euros lifts the value of KKR's offer, which is conditional on the government's backing and the outcome of a four-week due diligence analysis, to 33 billion euros.

TIM said on Sunday KKR had termed as "friendly" its offer of 50.5 euro cents per TIM share, a 45.7% premium to the closing price of the group's ordinary stock on Friday.

The price, which TIM said was "indicative", would expose the company's top investor Vivendi to a steep loss on its 24% stake, for which it spent on average 1.07 euros per share.

A person close to the French media group told Reuters Vivendi believed KKR's offer did not adequately value TIM.

TIM's board did not give a view on the proposal. ($1 = 0.8872 euros) (Reporting by Valentina Za; editing by Agnieszka Flak)