* EDF expects decision on tariffs in coming weeks
* End to safety outages boosts nuclear production
* Dalkia and EDF EN revenue now reported separately (Adds CFO comments)
PARIS, May 9 (Reuters) - Electric power utility EDF said improved availability of its French nuclear power stations and higher tariffs boosted first-quarter sales by 3.7 percent to 20.45 billion euros.
Chief financial officer Xavier Girre told analysts that EDF expects the French State Council to decide on regulated power tariffs in coming weeks, after an adviser to the Council last week recommended scrapping the tariffs, under which EDF sells power to most of its clients.
He declined to comment on the possible impact for EDF.
A decade after the French power market was opened to competition, EDF still sells about 85 percent of all electricity in France, with competitors such as Direct Energie trying to woo clients with market-based offers.
The long-delayed scrapping of regulated tariffs could speed up the client exodus at EDF, which lost nearly 1 million customers last year.
EDF said first-quarter nuclear electricity production in France rose 4.1 percent to 113 terawatt-hour (TWH) - in line with its forecast for nuclear output greater than 395 TWh in 2018 - as nearly all its reactors are now back on line following a series of safety-related outages last year.
The company also confirmed its 2018 earnings guidance for core earnings of 14.6 to 15.3 billion euros and cash flow that is slightly positive or close to balance, excluding investments in its Linky smart meters and asset disposals.
Sales from French generation and supply were up 0.2 percent to 7.9 billion euros, sales from regulated activities up 6.7 percent to 5.2 billion euros, UK sales up 0.4 percent to 2.6 billion euros and sales in Italy were up 4.8 percent to 2.6 billion euros.
EDF also for the first time detailed the revenues of its Dalkia energy services unit and its EDF Energies Nouvelles unit, which had first-quarter revenues of 1.2 billion euros and 379 million euros respectively.
While overall first-quarter sales were up 3.7 percent from a restated 19.7 billion euros in Q1 2017, they were down 3.2 percent compared to the 21.13 billion euro first-quarter revenue published a year ago.
Girre said new accounting rules no longer allow EDF to recognise the delivery component of energy supply contracts and some market trading activities as revenue. The revenue reduction is offset by a similar reduction in fuel and energy purchases and will have no impact on core earnings, he added. (Reporting by Geert De Clercq Editing by Bate Felix and Alexander Smith)