UPDATE 2-Bertelsmann looks at costs after weak ads hit Q1

* Says Q1 sales down 8 pct, EBIT down 54 pct

* Posts net loss

* Still sees 2009 sales, EBIT lower, but no details

* Plans to focus on cost savings

(adds detail, background)

By Nicola Leske

FRANKFURT, May 12 (Reuters) - Bertelsmann [BERT.UL], Europe's largest media group, hopes to mitigate declines in sales and earnings this year with strict cost savings as falling advertising revenues led to a first-quarter net loss and shaved almost 8 percent off sales.

The owner of broadcaster RTL AUDK.LU and publisher Random House on Tuesday reiterated it expected 2009 sales and operating profit to fall from last year's level but did not give more details.

"The degree of year-on-year change will depend on the intensity and duration of the economic downturn," it said.

Bertelsmann said it now planned to focus on cost cuts to minimise the impact of the economic crisis on the the group.

Chief Executive Hartmut Ostrowski said in an interview with German daily Frankfurter Allgemeine Zeitung earlier this month that the company had launched the biggest cost saving programme in its history.

"The sluggish advertising market has made our magazines thinner. TV series have fewer interuptions from commercials," Ostrowski told the paper and added that on average ad markets had dropped around 10 percent.

"We need to react to that," he said.

Bertelsmann said earnings before interest and tax (EBIT) in the first three months fell by more than 50 percent to 115 million euros ($156.5 million) on sales of 3.5 billion.

The Guetersloh-based company posted a net loss of 78 million euros compared with a net profit of 35 million a year earlier.

The company generates around 30 percent of revenue from advertising.