Opec leaders meeting at the weekend summit in Saudi Arabia have differed sharply over the group strategy and purpose, but have united in defence of high oil prices.

Hugo Chávez, the left-wing president of Venezuela, opened the summit welcoming oil prices at close to $100 a barrel, describing them as “fair”. He called for the group to be “an Opec for geo-politics, an Opec for revolution”, adding “Opec was born as a geo-political actor, not as an economic or technocratic bloc.”