The Russian gas behemoth Gazprom announced Monday second-quarter net profit of 293.8 billion rubles, an increase of 29 percent over a year earlier, thanks to a weak ruble.

April-June net profit -- equal to $4.57 billion or 4.08 billion euros -- rose by around 100 billion rubles over the same period in 2014 due to currency factors, it said.

Turnover fell back four percent to 1,265 billion rubles, the company said.

Most of Russian gas behemoth Gazprom's costs are in the battered Russian currency, while most of its revenues are in dollars or euros.

Russian gas behemoth Gazprom has also been badly hit by the slump in oil prices and by a US ban on technology transfers to Russia for specific energy projects.

The firm's market capitalisation has plummeted in recent years.

Prior to the 2008 financial crisis, Gazprom was worth more than $300 billion.

Its value now hovers around $50 billion, trailing far behind the world's other major energy companies.