TIM's landline grid should carry at least 10 billion euros of the company's debt were it to be separated from the group's services arm, the person said, asking not to be named because deliberations are confidential.

Vivendi owns 23.8% of TIM and its support is important for any asset separation deal to go through.

TIM's new CEO Pietro Labriola is working on a revamp plan for the debt-laded phone group centred on the separation of the company's wholesale fixed network operations from its services businesses.

As part of the plan, TIM is considering an outright sale of its domestic landline grid and its international cable unit Sparkle, sources have previously said.

TIM last month signed a non-binding accord with state lender CDP - TIM's second-biggest investor - to create a unified broadband champion in Italy combining TIM's network assets with those of CDP-controlled rival Open Fiber.

The source close to Vivendi said the French media group was a long-term investor in TIM and, following a split, would focus its strategic efforts on the group's services arm which it rules out selling.

TIM declined to comment.

($1 = 0.9511 euros)

(Reporting by Elvira Pollina; editing by Valentina Za)

By Elvira Pollina