The UN's annual report on global food security confirms that more than one billion people - a sixth of the world's population - are undernourished.
It says the number of hungry people was growing before the economic crisis, which has made the situation worse.
The report comes ahead of World Food Day on Friday.
"No nation is immune and, as usual, it is the poorest countries and the poorest people that are suffering the most," said the annual report of the UN's Food and Agriculture Organization (FAO) and the World Food Programme.
The FAO says Asia and the Pacific has the largest number of hungry people - 642 million - followed by Sub-Saharan Africa with 265 million.
"FAO estimates that 1.02 billion people are undernourished worldwide in 2009," it said. "This represents more hungry people than at any time since 1970 and a worsening of the unsatisfactory trends that were present even before the economic crisis."
It added: "The World Food Summit target of reducing the number of undernourished people by half to no more than 420 million by 2015 will not be reached if the trends that prevailed before those crises continue."
The report, released in Rome, says the economic downturn has reduced foreign aid and investment in poorer countries and cut remittances from those working abroad.
It says the loss of income is compounded by food prices that are "still relatively high".
The UN agencies are urging international investment in agriculture and economic safety nets for poorer countries "despite financial constraints faced by governments around the world".
FAO Director General Jacques Diouf is to present a "toolbox" for helping countries to fight hunger on Thursday.
The Global Hunger Index - a survey published by the International Food Policy Research Unit (IFPRI) - reveals that the Democratic Republic of Congo has seen the steepest rise in hunger since 1990, followed by Burundi, the Comoros and Zimbabwe.
However, it says some countries have dramatically improved levels of malnutrition since 1990, including Vietnam, Brazil, Saudi Arabia and Mexico.
The survey describes a "food price crisis", with prices settling at levels too high for many people in developing countries.
The survey suggests that empowering more women in developing countries through education and better access to jobs is a key to reducing world hunger.
14 October 2009 – The economic turmoil sweeping the globe has lead to a sharp spike in hunger affecting the world's poorest, uncovering a fragile global food system requiring urgent reform, according to a report issued today by two United Nations agencies.
The combination of the food and economic crises have pushed more people into hunger, with the number of hungry expected to top 1 billion this year, according to the Food and Agriculture Organization (FAO).
The agency, along with the World Food Programme (WFP), said in their "The State of Food Insecurity" report that nearly all of the world's undernourished live in developing countries.
Even before the onset of the current crises, the number of hungry has been growing slowly and steadily over the past decade, it noted.
Strides in improving access to food were made in the 1980s and early 1990s, thanks to stepped up agricultural investment after the global food crisis of the early 1970s. However, official development assistance (ODA) fell between 1995-1997 and 2004-2006, resulting in surges in the number of undernourished in most regions.
The increase in the number of the world's hungry in times of both low prices and economic prosperity as well as periods of price spikes and recessions shows how weak the global food security governance system is, according to FAO.
"World leaders have reacted forcefully to the financial and economic crisis and succeeded in mobilizing billions of dollars in a short time period," said Jacques Diouf, the agency's Director-General. "The same strong action is needed now to combat hunger and poverty."
The world has the economic and technical know-how to eradicate hunger, but the political will is missing, he stressed.
"Investing in agriculture in developing countries is key as a healthy agricultural sector is essential not only to overcome hunger and poverty, but also to ensure overall economic growth and peace and stability in the world."
For her part, Josette Sheeran, Executive Director of WFP, said that speedy action is crucial to address food insecurity.
"At a time when there are more hungry people in the world than ever before, there is less food aid than we have seen in living memory," she said. "We know what is needed to meet urgent hunger needs – we just need the resources and the international commitment to do the job."
with this single comment on biofuels, having reported that cereal crop yield increases are slowing down (hardly a surprise?):
"Given the increased importance of biofuels and the new
linkages between agricultural and energy markets, increased
cereal yields, if achieved, may not necessarily continue to
lead to lower cereal prices. Because the world energy market
is so much larger than the world grain market, grain prices
may be determined by oil prices in the energy market as
opposed to being determined by grain supply. Even if this
proves to be the case, however, higher cereal yields will still help reduce poverty by raising revenues for small farmers
and increasing demand for rural labour. Thus, it is time to
learn from the past and re-invest in the agriculture sector to
reduce food insecurity and poverty."