Ahead of a global summit on the food crisis, the United Nations called on world leaders on Wednesday to agree to urgent measures to ease demand for grains and ease high food prices. A report by the Food and Agriculture Organisation of the United Nations suggested that countries might need to reconsider policies that encourage the production of ethanol and other biofuels. The report also suggested that the food summit in Rome, which will run from June 3 to 5, will give world leaders a chance to renew a war on hunger.,