By Grant Ferrett
BBC News
A United Nations expert has condemned the growing use of crops to produce biofuels as a replacement for petrol as a crime against humanity.
The UN special rapporteur on the right to food, Jean Ziegler, said he feared biofuels would bring more hunger.
The growth in the production of biofuels has helped to push the price of some crops to record levels.
Mr Ziegler's remarks, made at the UN headquarters in New York, are clearly designed to grab attention.
He complained of an ill-conceived dash to convert foodstuffs such as maize and sugar into fuel, which created a recipe for disaster.
Food price rises
It was, he said, a crime against humanity to divert arable land to the production of crops which are then burned for fuel.
He called for a five-year ban on the practice.
Within that time, according to Mr Ziegler, technological advances would enable the use of agricultural waste, such as corn cobs and banana leaves, rather than crops themselves to produce fuel.
The growth in the production of biofuels has been driven, in part, by the desire to find less environmentally-damaging alternatives to oil.
The United States is also keen to reduce its reliance on oil imported from politically unstable regions.
But the trend has contributed to a sharp rise in food prices as farmers, particularly in the US, switch production from wheat and soya to corn, which is then turned into ethanol.
Mr Ziegler is not alone in warning of the problem.
The IMF last week voiced concern that the increasing global reliance on grain as a source of fuel could have serious implications for the world's poor.