Amid growing warnings that nearly 13 million people are facing famine in southern Africa, UN Secretary General Kofi Annan called for greater access to land, credit, markets and technology for the world's farmers.
The meeting - hosted by the UN's Food and Agriculture Organisation (FAO) - is a follow-up to a summit five years ago which pledged to cut the number of people starving around the world by half by the year 2015.
Only a fraction of this target has been reached so far and hopes that efforts to combat hunger would be revived have been undermined by the fact that only two leaders from Western nations - Spain and Italy - are attending the meeting.
The head of the FAO, Jacques Diouf has openly accused the developed world of indifference.
But with a looming famine in Southern Africa and the World Food Programme appealing for urgent funds to supply grain, it is easy for rich country governments to assume that all they are being asked to do is open their cheque books, says the BBC's Elizabeth Blunt.
Mugabe controversy
Most heads of state from developing countries are present, including Zimbabwean President Robert Mugabe.
He has been allowed to attend the meeting despite a travel ban imposed on him by the European Union, as heads of state are allowed access to all UN conferences.
Western governments have blamed the Zimbabwean leader for exacerbating food shortages in his country through encouraging seizures of white-owned farms by his supporters.
In his speech at the summit, he defended his land redistribution programme and said the important thing was to enable African countries to feed themselves.
"I think the most important aspect should be on how we can get the developing world, that is the world where hunger is, to marshal resources so production can go up of food stuffs," he said.
Global hunger
1996: 840 million hungry people
2002: 815 million hungry people
2015 target: 400 million hungry people
South African President Thabo Mbeki called on rich countries to lift trade barriers which prevent farmers from poorer countries exporting food to their markets.
His call was reinforced by the Ugandan President, Yoweri Museveni, who spoke of the need for African farmers to raise their sights beyond mere subsistence agriculture.
In order to meet its aim of reducing the number of hungry people to 400 million by 2015, the FAO is seeking an additional $24bn a year in agricultural and rural investment.
Since 1996, when the target was set, the number of hungry people has only dropped from 840 million to 815 million.
To reach the target, the number has to decline by 22 million people each year, but the UN says the figure is dropping by only six million a year.