The rise of biofuels is not only adding to the global food price crisis but also poses a risk for peasants, pushed off their land to make way for energy crops, a report prepared for this week's food summit said.
The use of food such as maize, palm oil and sugar to produce fuel has been blamed in part for record high commodity prices which are driving millions of people into hunger, and will be a key issue discussed by world leaders at the Rome summit.
Condemned as a "crime against humanity" last year by the then UN food rapporteur, Jean Ziegler, critics of biofuels say they divert nutrition away from mouths and into fuel tanks and compete for land that should be used to grow food.
Both the US and the EU have policies promoting the use of biofuels as alternatives as a way to reduce reliance on crude oil.
The report, published yesterday by the Food and Agriculture Organisation (FAO) that hosts the three-day summit from today, flagged up several social and environmental risks of biofuels, but said they were not the main cause of the food crisis.
"Recent hikes in world food prices have not been caused primarily by biofuels," it said, listing the main reasons for the price hikes as poor harvests, low stocks and rising demand in Asia for food and fodder.
Co-written by the FAO and the London-based International Institute for Environment and Development and (IIED), the report, "Fuelling exclusion? The biofuels boom and poor people's access to land", said the biofuels boom was a major threat to millions of peasants.
An estimated 1 percent of the world's arable land is used for biofuels, a figure that will rise to between 2.5 and 3.8 per cent by 2030, depending on policy incentives, according to International Energy Agency figures.
Some peasant farmers could benefit from the boom if they have access to land to grow the increasingly profitable cash crops, but other are likely to be driven off land required for large-scale plantations, the report said.
"Specific social groups such as pastoralists, shifting cultivators and women are especially liable to suffer exclusion from land caused by rising land values, while people who are already landless are likely to see the barriers to land access increase further," it said.
Some biofuel crops could be an opportunity for pastoralists living on scrubby land, such as the jatropha shrub, already being cultivated in Mali to fuel power plants, the report said.
But it recommended new standards to ensure land rights of poor people, including certification schemes for biofuels to ensure they are produced without destroying the local environment or abusing the rights of local people.