UPDATE 1-Argentine growth above 9 pct two months in a row

(Adds details, background; analyst comment)

BUENOS AIRES, Nov 15 (Reuters) - Argentina's economy grew a bigger-than-expected 9.1 percent in September from the same month last year, recording its second straight month of expansion above 9 percent, the government said on Thursday.

The figure was well above the 8.5 percent median forecast given in a Reuters poll of 12 analysts, whose estimates ranged between 8.0 percent and 9.0 percent.

The number confirmed what an official source told Reuters earlier in the day. The statistics institute reports the EMAE economic activity index ARECI14 without providing details on sectors.

Merrill Lynch, which had forecast Argentina's September growth at 8.9 percent, anticipated in a report this week that "strong industrial output and services growth (would) boost activity and offset a negative calendar effect."

In September, Latin America's No. 3 economy also showed growth of 0.9 percent versus August.

Argentina is on track to record its fifth straight year of annual growth above 8 percent, thanks to strong private spending, industrial production and agricultural exports.

President Nestor Kirchner said earlier on Thursday in a speech that "better times are on their way." His wife, Sen. Cristina Fernandez de Kirchner, will take office as Argentina's first female president on Dec. 10.

She faces the challenge of lowering inflation, restoring credibility to the INDEC national statistics institute, and boosting energy supplies amid soaring demand.

Industrial output slowed in June and July as the government cut power and natural gas flows to major users to safeguard residential supplies during the southern hemisphere winter.

Some analysts believe factories are speeding up production now in anticipation of another energy crunch during the summer, when air-conditioning use surges.

The EMAE measures most elements of gross domestic product, which the government reports quarterly. Third-quarter GDP figures are scheduled to be released on Dec. 13.

Argentina's economy grew 9.2 percent in August of this year and 8.5 percent year-on-year in September 2006. (Reporting by Hilary Burke, Editing by Chizu Nomiyama)