The rising price of cereals such as wheat and maize is a "major global concern", the United Nations' Food and Agriculture Organization (FAO) says.
Wheat prices have risen 83% in the past year
Poor countries could see their cereal import bill rise by more than a third. Africa as a whole is expected to see an estimated 49% increase this year.
International wheat prices have risen 83% in the past 12 months.
Demand from emerging countries such as China, and droughts and flooding have pushed cereal prices to record highs.
CEREAL IMPORT BILLS
Africa up 49%
Asia up 25%
Latin America up 31%
Oceania up 25%
Europe up 53%
It is estimated poor countries will pay a record $33.1bn (£17bn) for cereal imports in the year to July 2008. This is despite a fall in the total amount they will import.
In an attempt to limit the impact of rising prices on their populations, governments have lowered import tariffs, raised food subsidies and imposed duties on food exports.
The rising price of wheat, maize and rice will push up the cost of basic foods and this will affect the world's vulnerable populations the most, the FAO said.
It warned 36 countries around the world were facing a food crisis.
The highest number of countries facing a severe shortage of food - 21 - is in Africa.
Lesotho, Somalia and Swaziland are said to be facing an "exceptional shortfall" in food supply after years of adverse weather.
The FAO this week launched an appeal for $87m of emergency assistance to help flood-affected populations in Mozambique, Zimbabwe, Zambia and Malawi.
Farmers in flooded areas are in urgent need of seeds to begin replanting, with only two months to the end of the cropping season, the FAO said.