UPDATE 1-EDF ups stake in Austria's Estag to 25 pct

PARIS, June 26 (Reuters) - French utility EDF (EDF.PA) said on Friday it had increased its stake in Austrian energy supplier Estag to 25 percent from 20 percent by buying GDF Suez's (GSZ.PA) 20 percent stake in a holding company.

EDF said it is now the sole shareholder in Societe d'Investissement en Autriche (SIA), which owns 25 percent of Estag.

Land of Styria owns the remaining 75 percent of Estag, which operates in the energy and waste management sectors with has around 40 subsidiaries in Austria. Austrian newspaper Der Standard reported on Thursday that EDF was planning to sell its stake in Estag to Verbund (VERB.VI), Austria's largest utility.

Der Standard said EDF would first buy out GDF Suez and then offer the stake to Verbund, without saying where it got the information.

(Reporting by Helen Massy-Beresford; editing by John Stonestreet)