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* Net profit up 2 pct, revenue down 6.4 pct
* Cost controls help offset fall in oil prices
* Net debt down 47 pct to $23.2 bln
* Prepayments stood at 938 bln roubles in 2015 (Adds details from conference call)
By Vladimir Soldatkin
MOSCOW, March 31 (Reuters) - Russia's Rosneft onThursday reported a 2 percent rise in 2015 net profit to 355billion roubles ($5.2 billion) and a sharp fall in debt, easingconcerns over the financial health of the world's top listed oilproducer by output.
Oil companies, important sources of income for Russia'sstate budget, have struggled with a sharp fall in global crudeprices since mid-2014.
They have also been hit by Western sanctions imposed onMoscow in 2014 for its role in the Ukraine crisis.
Rosneft, in which BP owns 19.75 percent, saidearnings were supported by cost controls despite a 16 percentfall in the price of Russian flagship Urals crude blend inrouble terms.
Rosneft said its 2015 earnings before interest, tax,depreciation and amortisation (EBITDA) rose by almost 18 percentto 1.25 trillion roubles on revenue of 5.15 trillion roubles,down by 6.4 percent.
Fourth-quarter net income fell by almost 53 percent to 53billion roubles, it said.
The company, headquartered across the Moskva river from thered brick walls of the Kremlin, has risen to prominence underthe leadership of Igor Sechin, a long-standing ally of RussianPresident Vladimir Putin, thanks to various acquisitions.
It amassed huge debts while buying TNK-BP, the Anglo-Russianfirm, in 2013 for $55 billion. The company plans to pay back$14.3 billion in debt this year.
Rosneft said its net debt fell by 47 percent to $23.2billion as of the end of the year due to prepayment underlong-term oil supply contracts.
Analysts have expressed concern over the level of debt,worrying that the spending could spiral out of control.
Rosneft has said it would boost capital expenditure to 1trillion roubles annually in 2016-2018 from around 600 billionin 2015, aiming to maintain output at mature fields.
"The question is what will happen this year (with spending).Rosneft has quite ambitious investment plans, it would beinteresting to see where they will invest," Alexei Kokin, ananalyst from UralSib brokerage said.
PREPAYMENT
After introduction of sanctions, which shut down Westerncapital markets for the company, Rosneft switched to prepaymentdeals with international traders, such as Trafigura.
It said in 2015, prepayments totalled 938 billion roubleswithout disclosing the source of the funds.
Rosneft shares were down by 1.1 percent in late trade,underperforming a 0.27 percent decline on the broader Moscowstock market.
The company has struggled to maintain output at maturefields in Western Siberia, home to around two-thirds of Russia'soil production.
Rosneft said this week oil production slipped 1 percent lastyear to 202.8 million tonnes (4.07 million barrels per day).
A company official told a conference call that he sees oilproduction flat this year.
($1 = 67.8650 roubles) (Reporting by Vladimir Soldatkin, additional reporting by DenisPinchuk; editing by Dmitry Solovyov and David Evans)
