Sources familiar with the matter told Reuters last week that Vivendi had taken steps to increase its holding in Telecom Italia to around 19 percent, giving Vivendi's chairman Vincent Bollore a key position at a time when the mobile telecoms industry is consolidating and the indebted Italian company is seen as a possible takeover target.

The stake-building makes Bollore, Vivendi's biggest shareholder, a major player in European telecoms again only months after Vivendi finished selling off all three of its main telecoms interests - French mobile network operator SFR, Maroc Telecom and GVT.

"This new investment confirms Vivendi's intention to support the (Italian) telecoms group over the long term and to develop its activities in southern Europe," Vivendi said in a statement on Tuesday.

Vivendi became Telecom Italia's biggest shareholder in June when it took an 8.3 percent stake off the hands of rival Spanish group Telefonica as part-payment for selling its Brazilian broadband telecoms group GVT to Telefonica Brasil.

The French company then began buying additional shares following the dissolution of the Telco investment vehicle that once held 22.4 percent of Telecom Italia on behalf of Telefonica and three Italian financial institutions.

Vivendi said on Tuesday it had since bought shares on the market to take its stake in Telecom Italia to 19.9 percent. Its stake previously stood at 15.49 percent.

Altogether Vivendi said it had spent 3.05 billion euros or around 1.14 euros per ordinary share on acquiring its stake. At current market prices the stake is worth around 2.85 billion euros.

Telecom Italia shares were down 1.2 percent at 1.06 euros by 0805 GMT.

(Reporting by Valentina Za; Editing by Himani Sarkar and Greg Mahlich)

Stocks treated in this article : Vivendi, Telefonica SA, Telecom Italia SpA