Press Association: Biofuels have caused world food prices to go up by 75%, it has been reported. The Guardian said it has seen the figure in a confidential World Bank report which contradicts US government claims that using plants to produce fuel contributes less than 3% to food prices. According to the paper, sources believe the analysis – carried out by a respected economist at the global financial body – has not been published to avoid embarrassing US President George Bush. The leaked …