Gazprom has announced a sharp rise in profits thanks in large part to a weak Russian ruble.

The Russian energy giant’s net profit for Q1 2015 was 382 billion rubles ($5.9 billion), up 71% on a year earlier. Total sales rose 6% to 1.65 trillion 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 132 billion cubic meters of gas.

This fall was partly due to sanctions imposed by the West following Russia’s actions in the Ukraine.

It meant Gazprom shares were down almost 2% in trading in Moscow despite the jump in quarterly profits.

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.