(Adds background)
    MILAN, Dec 23 (Reuters) - An Italian administrative court
has annulled a watchdog ruling capping the stake of French media
giant Vivendi  VIV.PA  in Mediaset  MS.MI , a court document
showed, in a blow to the broadcaster run by ex-prime minister
Silvio Berlusconi's family.
    Vivendi and Mediaset have been at odds since 2016 when the
French group ditched an accord to buy Mediaset's pay-TV unit and
built a 29% stake that the Italian group considers hostile.
    Vivendi was forced to transfer two thirds of its voting
rights in Mediaset into a trust after Italy's communications
regulator ruled in 2017 that Vivendi's stakes in Mediaset and in
Telecom Italia (TIM)  TLIT.Mi  ran counter to laws protecting
media plurality.
    The French group is TIM's biggest shareholder with a 23.9%
stake and Mediaset's second-largest with a 28.8% holding
although its voting rights in the broadcaster have been reduced
to 10%.
    Following a favourable ruling by the European Union's top
court, Vivendi has been seeking to regain voting rights for its
full stake in Mediaset, asking the Italian administrative court
TAR del Lazio to annul AGCOM restrictions.
    Mediaset declined to comment on the court document seen by
Reuters on Wednesday. A legal source, speaking on condition of
anonymity, said Mediaset will appeal the decision.
    Vivendi was not immediately available to comment.

 (Reporting by Domenico Lusi and Elvira Pollina; editing by
Giselda Vagnoni and Barbara Lewis)
 ((stephen.jewkes@thomsonreuters.com; +39.0266129695; Reuters
Messaging: stephen.jewkes.thomsonreuters.com@reuters.net))