* Lagardere Active sales down 17 pct in Q3, ad sales down 8 pct
* Lagardere still aims for flat 2012 media operating profit
* Bertelsmann stops short of repeating net profit outlook
* Lagardere shares down 2 pct
By Dominique Vidalon and Harro Ten Wolde
PARIS/FRANKFURT, Nov 13 (Reuters) - Headwinds facing Europe's media sector have buffeted Lagardere, Bertelsmann and its RTL unit, as the economic slowdown hits ad spending and makes the outlook more uncertain for publishers and others in the sector.
French media-to-aerospace group Lagardere posted a slump in sales at its print and broadcasting division, while publisher Bertelsmann and broadcaster RTL warned the economic crisis in Europe could weigh on earnings this year.
Their comments are the latest sign of difficulties facing the sector, after other media and advertising groups such as Publicis, WPP and Omnicom cited economic headwinds as the main cause for declining advertising income.
ProSiebenSat.1, RTL's biggest competitor in Germany, last week reported a drop in German ad sales.
Bertelsmann, which also owns publishers Gruner + Jahr and Random House, previously said it saw a rise in net profit in 2012, but stopped short of repeating that outlook on Tuesday.
It said group profit would be impacted by special items in the print business and several direct-to-customer businesses, as well as from its operations in southern Europe.
"Also, the subdued economic outlook and the euro crisis make it difficult to predict our future performance at this point," it added.
At France's Lagardere there was a 17 percent sales slump in Lagardere Active, the group's magazines and radio division, in the third quarter. The unit accounts for roughly a fifth of group revenue and is the most sensitive to the advertising cycle.
Advertising revenue in the unit, which owns radio stations in France and Belgium, fell 8 percent, which was slightly worse than expected, CM-CIC analysts said in a note.
By 0902 GMT, Lagardere shares were off 2 percent at 20.60 euros, underperforming the European media sector, though the group as a whole kept its annual profit target.
Strong book publishing sales, boosted by the launch of new titles such as J.K. Rowling's "The Casual Vacancy", helped offset the downturn at the Active division.
Lagardere, which competes with Pearson Plc and Bertelsmann in radio and book publishing, said it still expected its core 2012 media profit to be stable compared with 2011.
Third-quarter group revenue of 1.96 billion euros ($2.5 billion) compared with analysts' expectations of between 1.95 and 2.00 billion, according to a poll of six analysts.
Lagardere had in late August predicted that the second half of the year would be stronger than the first. [ I D:nL6E8JUG5F]
Bertelsmann said it still saw moderate revenue growth and high operating earnings before interest and tax (EBIT) for the full year.
Europe's largest media group, which said last month it would merge its publisher Random House with Pearson's Penguin, said revenue rose 5.7 percent to 11.4 billion euros over the first nine months of the year.
RTL said its TV advertising sales slightly increased in Germany, Europe's biggest economy, but said it still expected its 2012 operating profit to drop, citing an increasingly tough economic environment.
($1 = 0.7867 euros) (Editing by David Holmes)