UPDATE 1-France to decide on mobile licence by Xmas

* Iliad seeks to be fourth operator

* Decision to be made sooner than expected

By Leila Abboud

PARIS, Nov 10 (Reuters) - A decision to open France's mobile phone market to a fourth operator will be made by Christmas, telecommunications regulator ARCEP said on Tuesday.

ARCEP confirmed that Iliad SA's (ILD.PA) application - the only one submitted - was in order and would be reviewed in full. [ID:nLS389560]

Iliad, which built its success on triple-play offers of TV, fixed phone and broadband, is betting that an expansion into mobile will bring it new profits and help it compete with bigger rivals France Telecom (FTE.PA), SFR (VIV.PA) and Bouygues Telecom (BOUY.PA).

The entry of a fourth operator into France's 28 billion euro mobile market, Europe's third largest, has been hotly debated and is opposed by the existing operators.

For more background, click on [ID:nLK374445] and [ID:nLG310334]]

(Additional reporting by Marie Mawad; Editing by David Cowell)