Last year, the national communications authority (AGCOM) ordered Vivendi to cut its stake in one of the two companies within a year, ruling it was in breach of rules designed to prevent a concentration of power.

Vivendi, which aims to build a media empire in southern Europe, is the biggest single shareholder in Telecom Italia with a 24 percent stake and had accumulated a 28.8 percent shareholding in private broadcaster Mediaset, controlled by the family of former Prime Minister Silvio Berlusconi.

Vivendi appealed AGCOM's decision but in April this year it transferred 19.19 percent of its stake in Mediaset to a trust called Simon Fiduciaria to comply with the order.

A ruling in favour of Vivendi could mean the French group gets back ownership of the stake it transferred.

"There will be a decision no earlier than 45 days, but more probably after the summer," one of the sources said.

One of Vivendi's lawyers did not rule out a possible complaint to the European Commission on the issue.

"Vivendi has not presented a complaint to the EU Commission because it has full confidence in Italy's justice system which applies EU laws. But if that is not the case we will call on the Commission," one of Vivendi's lawyers, Giuseppe Scassellati Sforzolini, said.

Vivendi's lawyers have argued the decision by AGCOM is discriminatory and goes against both Italian and European rules given Vivendi does not exercise a dominant influence on Mediaset.

At its latest shareholder meeting, Milan-based Mediaset, closed the doors of its AGM to the trust, preventing it from exercising its voting rights. Vivendi decided not to present a slate of candidates for the new 15 member Mediaset board.

(Reporting by Domenico Lusi and Stefano Rebaudo, Writing by Giulia Segreti; Editing by Elaine Hardcastle and Mark Potter)