In September Italy began to look into the failure by TIM's top investor Vivendi - which holds a 24 percent stake in the company - to communicate to the prime minister's office that it had de facto control over the former monopoly.

Vivendi had repeatedly denied controlling Italy's largest phone company although the French media group had gradually tightened its grip on TIM since first buying a stake in 2015.

After months of friction between Vivendi and the Italian government, Rome in October applied the so-called "golden power", allowing the government to veto strategic decisions such as asset sales and mergers at businesses deemed to be of strategic national importance.

The move was widely seen as a bid to rein in Vivendi's influence.

But last week TIM entered a new phase as U.S. hedge fund Elliott, which built a stake of 9 percent in TIM, pulled of a boardroom coup, wrestling control away from Vivendi and securing two-thirds of the available seats on the company's board.

Industry minister Carlo Calenda said earlier this year that the fine would be applied "because we are a country that wants rules to be respected".

TIM said in a statement it should not be identified as the entity responsible for incurring the fine and reserved the right to consider the issue further.

TIM also reiterated that it had already filed an appeal on the issue, arguing that it did not have any notification obligations given that it had not taken decisions which involved the disposal of the group's strategic assets.

"Given also the changed governance of the company, TIM confirms its unconditional desire to collaborate with the government to ensure it is fully in harmony with all prescriptions to safeguard national security," the statement added.

On Monday TIM said it had temporarily given its head of security, Stefano Grassi, powers to manage all assets deemed strategic for national security and defence.

(The story corrects typographical error in paragraph 6. Also adds Vivendi's Reuters Instrument Code in paragraph 2)

(Reporting by Giulia Segreti; Editing by Gopakumar Warrier)