In a document presenting Bluebell's vision for TIM, seen by Reuters, it proposed Laurence Lafont, the outgoing vice-president for strategic industries at Google Cloud in Europe, as candidate for the role of TIM CEO.

TIM investors are due to meet on April 23 to appoint a new board of directors.

Representatives for Bluebell, which holds a 0.5% stake in TIM, were not available to comment. Bluebell had filed a slate of nominees for TIM's board last month without indicating any candidate for the role of CEO.

The vote comes at a crucial time for the ailing former telephone monopoly, which is seeking a revamp centred on the sale of its domestic fixed-line access network to U.S. fund KKR.

In the document, Bluebell describes TIM's decision to sell its prized domestic fixed-line network to KKR as "flawed at inception".

"The only brief Bluebell provided to its board candidates is to review the status of the transaction, and act in the best interest of TIM and all its shareholders," the document said.

Labriola, whom TIM's outgoing board has proposed for reappointment, has also been challenged by minority investor Merlyn Partners, which has disclosed a 0.53% stake.

Merlyn is calling for a review of the terms of the network sale and is proposing a former TIM deputy general manager as CEO as part of a drastic overhaul of operations.

The sale of the network, backed by the Italian government, which indirectly controls 10% of TIM, is worth up to 22 billion euros. More than a half of TIM's domestic staff will move to the spun-off network business in the transaction, which is aimed at slashing TIM's debt pile.

TIM's top investor Vivendi has questioned the sustainability of the business left behind, and challenged the sale in court.

Vivendi, which left TIM's board last year after a round of fruitless negotiations with the government on the future of TIM, could use its 24% stake to obstruct Labriola's reappointment if it chose to back an alternative slate of candidates.

(Reporting by Elvira Pollina, editing by Gianluca Semeraro and Kevin Liffey)