* Q4 EBITDA down 5 pct to 319 mln eur
* Q4 net loss of 76 mln eur
* Outlook reiterated for 2013 sales to fall to 4.1 bln eur (Adds details, background)
VIENNA, Feb 28 (Reuters) - Telekom Austria reported core earnings fell 5 percent in the fourth quarter as its two biggest markets, Austria and Bulgaria, struggled with competition and regulation.
Adjusted earnings before interest, tax, depreciation and amortisation (EBITDA) were 319 million euros ($418 million) on flat sales of 1.12 billion euros in the quarter, the company said on Thursday.
Telekom Austria, in which Mexican billionaire Carlos Slim and his America Movil telecoms group built a 26 percent direct and indirect stake last year, reiterated its outlook for sales to fall to around 4.1 billion euros this year.
The company's sales and core profit beat expectations but it posted a bigger-than-expected net loss of 76 million euros for the quarter.
After slashing its dividend to conserve cash in September, the company said it still intended to pay a dividend of 0.05 euros for 2012 and 2013. It added that maintaining its BBB (stable) investment grade rating was its top priority.
"The management of the Telekom Austria Group expects the challenges that characterised the operational environment during 2012 to continue to dominate development in 2013," it said.
It named these as fierce competition in its mature mobile markets, further regulatory cuts to prices and fees, macro-economic headwinds and foreign currency risks. ($1 = 0.7628 euros) (Reporting by Georgina Prodhan; Editing by Michael Shields and David Cowell)