The USDA's annual Food Security Assessment said the number of "food-insecure" people in 70 developing countries rose to 982 million in 2007 from 849 million in the prior year.

The number of people struggling to obtain food could rise to 1.2 billion by 2017, USDA warned in a reversal of last year's forecast which saw the number of hungry people declining during the next 10 years in all regions, except Sub-Saharan Africa.

The USDA defines food insecurity as having difficulty acquiring enough food for the household throughout the year.

"Over the next decade, a slowdown in worldwide economic growth is projected to combine with food and fuel price hikes to contribute to an ongoing deterioration in global food security," USDA said.

"This will have a particularly negative impact on the developing countries that are already the most food-insecure -- those in Sub-Saharan Africa" such as Ethiopia, Eritrea, Sudan and Mozambique.

Prices for wheat, corn, soybeans and rice have surged to record highs in recent months amid disappointing global harvests, growing demand for biofuels and rising appetites for better diets.

Around the world, rising food prices have lead to hoarding, bread lines and food riots.

Poor countries are especially susceptible to rising food prices because food costs account for more of each household's total household expenditures. USDA said food can account for more than half of a family's budget in some countries.

USDA said global food aid also is under pressure. During 2004-2006, food aid fell to about 7.4 million tonnes, a drop of 25 percent.

Rising food prices and transportation costs have prompted the United States, the world's largest food aid donor, to cut shipments by roughly 50 percent during the last 5 years.