(CNN) -- World Vision, one of the world's largest humanitarian organizations, announced Tuesday that it cannot feed 1.5 million of the 7.5 million people it fed last year and made an urgent appeal for international donors to step in.
The price of wheat flour went up an average of 60 percent across Afghanistan last year.
The cutback could affect donations to 35 of the 100 countries in which the agency works, said Rachel Wolff, media relations manager for disaster response.
The cutbacks are occurring across the developing world. Some of World Vision's food aid programs have been cut altogether, such as those in East Timor and Sri Lanka, while others have been reduced, such as those in Burundi, Niger, Cambodia, North and South Sudan. The cuts affect people in nearly every region of the world.
In Haiti, where food riots forced a change in government last week, the next major food shipment is not expected before June, and that will not meet the need, Wolff said.
"Though we're able to feed people, we're not feeding people as we would like, and those people we are feeding are getting less than we would like."
She cited two primary, interconnected causes: an increase in food prices and an increase in the need for food.
Wolff said the magnitude of the shortfall is unprecedented and predicted that the situation "probably will get worse as the year progresses."
"What's unique about this is that it's happening all over the world," she said.
Among the causes is the diversion of corn to the production of ethanol rather than food, she said.
The spiraling price of fuel has aggravated the problem by boosting the cost of fertilizer and transporting food.
Wolff said child health experts worry that the impact of even a short period of malnutrition will endure for years.
"If the world community doesn't invest this now, everybody will pay for it later," she said. "You will have massive economic implications for these countries. Their work force won't have developed properly. Not to mention that it's horrific from a humanitarian standpoint. Those are the things we're sounding the alarm on."
The cutbacks have already begun, said Dean Hirsch, president of World Vision International, in a written statement. "Despite our best efforts, more than a million of our beneficiaries are no longer receiving food aid."
More than half of them are children, he said.
He predicted the crisis will take at least two years to stabilize, "far too long for the millions of children who need sufficient levels of nutrition now to develop properly."
The World Bank has also expressed dismay.
"Based on a very rough analysis, we estimate that a doubling of food prices over the last three years could potentially push 100 million people in low-income countries deeper into poverty," World Bank President Robert B. Zoellick said in Washington last week. "This is not just a question of short-term needs, as important as those are; this is ensuring that future generations don't pay a price, too."
He has called for a "New Deal for Global Food Policy" to meet the crisis, as well as $500 million -- about half of which has been met -- from donor governments to close a gap identified by the United Nations' World Food Programme.
But World Food Programme spokeswoman Bettina Luescher said Monday that the estimate had risen to $750 million over the past few weeks.
"We're in the middle of a perfect storm here," she said. "There are food riots going on in scores of countries."
She said the cost of rice in Cambodia has doubled in the past year, meaning that World Food Programme school lunch programs there may also end soon.
Taking away that safety net "can totally change their lives."
Such programs run on as little as 25 cents per child per day, meaning that even private individuals can have some effect, she said. "You can do it; I can do it; everybody can do it."
Those countries most affected face more than a humanitarian crisis. "It's also a peace and security issue," Wolff said. "That is why it is so important."
Malnutrition contributes to the deaths of more than 3.7 million children under 5 every year, according to World Vision, which began its work in 1950 by helping orphans of the Korean War.
Lack of food has also stunted the development of 147 million preschoolers in developing countries, the 31,000-member agency said. Malnourished children are also more likely to suffer and die from diseases like pneumonia, malaria and measles. E-mail to a friend 
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