US drivers are complaining about high petrol prices

Its revenues rose 32% on last year, also boosted by sales from Unocal, the oil firm it bought in 2005.

Combined with rivals ConocoPhillips and Exxon Mobil, three of America's oil giants have earned a combined $15.7bn during the first quarter of 2006.

Meanwhile, US drivers have seen petrol prices rise 16% in the last month.

Political measures

According to the Department of Energy, the average petrol price has now hit $2.91 a gallon, adding approximately $500 to the average household's annual bill.

The pain at the pump is now having political consequences.

US politicians are now considering a range of measures to lower oil prices, including handing out rebates to consumers, giving more incentives for people buying hybrid electric/petrol cars, slashing tax breaks for big oil firms and encouraging companies to build more oil refineries.