According to Mediaset's website, Vivendi owns 28.8 percent of Mediaset's shares.

"The decision of the Mediaset board is against all basic principles of shareholder democracy. It is both unlawful and against the interests of Mediaset and, in particular, of its minority shareholders," Vivendi said in a statement.

"Under these circumstances, Vivendi is not in a position to participate at the Mediaset shareholders' meeting and reserves all its rights to challenge in court the validity of the resolutions adopted today," it added.

(Reporting by Sudip Kar-Gupta; Editing by Jan Harvey)