Russian energy giant Gazprom has announced a sharp rise in profits thanks in large part to a weak ruble, BC News reports.

Net profit for the first three months of the year was 382bn rubles ($5.9bn), up 71% on a year earlier.

Total sales rose 6% to 1.65tn rubles.

Gazprom sells its gas in dollars, so a weak currency means the price of gas in rubles rises. The weak ruble helped to offset a fall in the volume of sales of almost 10%, to 132bn cubic meters of gas.

With the price of oil - which is a key determinant of the price of gas - back below $50 a barrel, many analysts believe Gazprom results for the rest of 2015 will be weaker than the first quarter.