The United Nations (UN) food agency has called on the United States to suspend its production of biofuel ethanol.
Under US law, 40% of the corn harvest must be used to make biofuel, a quota which the UN says could contribute to a food crisis around the world.
A drought and heatwave across the US has destroyed much of the country’s corn crop, driving up prices.
The US argues that producing much of its own fuel, rather than importing it, is good for the country.
The latest forecasts from the US Department of Agriculture (USDA) suggest that this year’s corn yield – the amount produced per acre – will be the lowest since 1995-6.
Total production will be the lowest for six years, it forecast, due to the extreme heat and dryness.
As a result, the USDA is predicting further rises in prices. It now thinks farm prices for corn will average $7.50-$8.90 per bushel, a sharp rise on the $5.40-$6.40 per bushel it predicted just a month ago.