Despite having reached an all-time high, US petrol prices are at a historical low in relation to crude oil prices, according to a study by a prominent think-tank at Rice University in Texas. Given stagnant or even falling demand at the pump, refiners are finding it difficult to pass oil price increases on to consumers.

Jim Mulva, chief executive of ConocoPhillips, the third biggest US oil and gas company and second biggest US refiner, said in an interview with the Financial Times refiners were only "breaking even" despite the outcry over rising petrol prices.