Parts of Africa are badly affected by hunger
Targets to cut the number of hungry people in the world will not be met without greater international effort, UN food agencies have warned.
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.