For decades the Organisation of the Petroleum Exporting Countries (Opec) has tried to control prices by cutting or raising supplies, which relied on all of its members sticking to agreed quotas.

Now Russia, which is not a member of the organisation, has exploited recent production cuts by Opec to gain market share, recently overtaking Saudi Arabia as the world's biggest producer.

Neave Barker reports from Moscow.

Source: Al Jazeera