BRUSSELS, Belgium (AP) -- Economist Jeffrey Sachs urged the United States and the European Union on Monday to reconsider a shift to biofuels that has helped increase food prices by turning agricultural land over to energy crops.

Targets to produce more fuels that release less carbon dioxide ''do not make sense now in a global food scarcity condition,'' Sachs, a special adviser to the United Nations, told reporters before he spoke to EU lawmakers at the European Parliament.

''In the United States, as much as one-third of the maize crop this year will go to the gas tank and this is a huge blow to the world food supply, so these programs should be cut back significantly,'' he said.

So far, the U.S. biofuel program has had more impact on food shortages, he said, but Europe's plans to rapidly boost biofuel output in coming years would also start to bite.

''Neither of them makes much sense actually in terms of the environmental effect, the energy balance, or the food impact, so I would advocate a reconsideration of both under the new market conditions,'' he said.

Sachs, the director of the Earth Institute at Columbia University, said it was unfair to blame financial speculators for soaring prices for basic foods such as wheat and rice.

''The fact inventories are very low, that food supply is more stagnant compared to food demand, gives a reason for speculators to try and buy, and hold grains in anticipation of tight conditions in future months and years,'' he said.

These underlying problems -- ''a tight food supply and vulnerability to climate shocks'' -- were not going to disappear and would need longer term solutions such as more development aid to poorer nations in Africa to help them increase food production, he said.

Last month, top international food scientists recommended a halt in the use of food-based biofuels, such as ethanol, because they say it would cut corn prices by 20 percent during a world food crisis.