Megafon sees slower sales growth, to raise investment

* Sees 2014 revenue rising by 6-8 pct after 9 pct in 2013

* To maintain core profit margin at at least 44 pct

* To increase capex to 58-64 billion roubles

MOSCOW, March 5 (Reuters) - Russia's second-biggest mobile phone operator Megafon (MCX: MFON.ME - news) said on Wednesday its sales growth would fall this year, echoing comments by rivals concerned over the impact of a sharp economic slowdown.

The company, controlled by Russia's richest man Alisher Usmanov, expects revenue growth in a 6-8 percent range in 2014, it said in a statement, down from 9.1 percent in 2013 when it generated 297.2 billion roubles ($8.2 billion) in sales.

Russia's largest mobile operator MTS said earlier that sales would rise by 3-5 percent a year in 2014-2016, compared with a reduced target of around 5 percent in 2013, citing poor economic growth prospects, and rival Vimpelcom forecast flat revenues for the coming year.

The "Big Three" operators, which together control more than 80 percent of the Russian mobile market, are under pressure to invest into next-generation mobile Internet networks as voice revenues have largely flattened out.

Megafon plans to increase capital spending to 58-64 billion roubles this year from 47 billion roubles in 2013.

It also said it aimed to maintain its core profit margin at at least 44 percent in 2014 after 44.6 percent last year.

In the fourth quarter, Megafon's net profit fell 46 percent to 10.1 billion roubles ($280 million), missing a 12 billion rouble average forecast in a Reuters poll.

The company said the fall was due to a one-off gain in the year-ago period, higher interest expenses and a revaluation of its foreign currency denominated debt.

Quarterly revenues grew 11 percent to 79.7 billion roubles and operating income before depreciation and amortisation (OIBDA) fell 2.9 percent to 30.5 billion roubles, giving a 38.3 percent margin. Analysts had forecast 78.7 billion, 31 billion roubles and 39.4 percent respectively.