* 9-month EBITDA 964 million euros, down 7 percent
* Clean energy arm hit by government power reforms
* Construction core profit down 18.8 percent (Adds impact from energy reform and earnings breakdown)
MADRID, Nov 12 (Reuters) - Spanish infrastructure and renewable energy group Acciona posted a 7 percent fall in nine-month core profit from a year ago, depressed by government energy reforms and a prolonged downturn in the domestic construction sector.
Spanish energy firms have been hit by a series of government power sector reforms aimed at plugging a gap between regulated prices and costs, including new levies on generation and lower subsidies and yields for wind and solar installations.
Acciona, whose clean energy division accounts for more than three quarters of underlying profit, has been particularly hurt by the measures, which it said have wiped 137 million euros ($184 million) from earnings so far.
Nine-month earnings before interest, taxes, depreciation and amortisation (EBITDA) totalled 964 million euros, in line with an average 959 million euros forecast in a Reuters poll, after an 8.5 percent decline at its energy arm.
Core earnings at the company's infrastructure business fell 18.8 percent as domestic construction activity continued to suffer from five years of recession or stagnation from which the economy has only just emerged in the third quarter.
The only bright spots in Acciona's results were its water division, with 25.4 percent annual EBITDA growth, and its services arm, where EBITDA grew 21.3 percent.
Nine-month net profit at Acciona, whose shares have lost 16.5 percent so far this year, declined 34 percent to 75 million euros from a year ago.
Net debt totaled 7.37 billion euros at end-September, down 1.5 percent from the end of 2012.
($1 = 0.7459 euros) (Reporting by Tracy Rucinski; Editing by Paul Day and Mark Potter)