Russian oil giant OAO Rosneft (ROSN.RS) Friday posted a net profit of 57 billion Russian rubles ($1.9 billion) in the fourth quarter of 2012, coming in below analysts' forecasts.

A Dow Jones survey of five analysts had forecast a net profit of RUB74.8 billion for the quarter.

State-controlled Rosneft said Friday Rosneft started reporting its results according to International Financial Reporting Standards (IFRS) for the first quarter of last year. The company didn't provide adjusted figures to compare the fourth quarter of 2012 with the same period a year earlier.

Rosneft's net profit for full year 2012 rose 7.2% on the previous year to RUB342 billion.

"Over the last year Rosneft has achieved significant strategic successes while also boosting operational efficiency," Rosneft President Igor Sechin said.

Revenue for the final three months of 2012 was RUB790 billion. Earnings before interest, taxation, depreciation and amortization, or Ebitda, was RUB144 billion.

Rosneft's production rose to 2.82 million barrels of oil equivalent per day.

The company's Ebitda margin, the measure used to judge a company's profitability, dropped to 19.8% in 2012 from 24.4% the previous year. With the net debt rising to RUB581 billion at the end of the fourth quarter from RUB542 billion at the end of the previous one, the net debt to Ebitda ratio reached 1.01 in the fourth quarter.

Increased investment and lower income from operations caused a sharp drop in free cash flow, which dropped to RUB45 billion for the full year from RUB99 billion a year before.

Rosneft is buying competitor TNK-BP from BP PLC (BP) and its partners in deals worth $5 billion which will create the world's largest traded oil producer. BP will increase its stake in Rosneft to 19.8% as part of the deal.