The price of rice has risen by 70% during the past year
The UN is to provide an additional $1.2bn (£613m) of food aid for 75 million people in the 60 nations hardest hit by rising food prices.
The announcement was made by World Food Programme chief Josette Sheeran at a UN-sponsored summit in Rome.
Also at the summit, UN Secretary-General Ban Ki-Moon said there was an "urgent need" for international policy guidelines on biofuel production.
Food costs have reached a 30-year high, causing riots in several countries.
The crisis is believed to have pushed 100 million people into hunger worldwide.
Ms Sheeran told a news conference that unless the international community acted quickly, the number of people in dire poverty could double.
"With soaring food and fuel prices, hunger is on the march and we must act now," she said.
Mr Ban said $15bn-$20bn (£7.6bn-£10.2bn) would be needed each year to boost food production to combat hunger.
He said he was encouraged that leading nations were beginning to recognise the size of the challenge, and singled out the French President, Nicolas Sarkozy, for praise.
On Tuesday Mr Sarkozy pledged $1.5bn over five years, specifically aimed at boosting production in Africa.
But Mr Ban added that, while he detected an increasing sense of urgency from leading nations about the food crisis, the international trade system needed to be made to work more effectively to make food available at reasonable prices.
He also called for more research into the impact of biofuels on the food crisis.
The International Food Policy Research Institute says biofuels are behind 30% of the global food price rises, while the US says biofuels are responsible for 2-3% of the rise.
The head of the World Bank, Robert Zoellick, called for the lifting of trade barriers that contribute to food price inflation.
"We need an international call to remove export bans and restrictions," Mr Zoellick told the news conference.
He told delegates the priority should be providing seeds, fertiliser and animal feed to farmers, before the planting season ends.
Kofi Annan, the former UN secretary general, said the solution to the current world food crisis had to include financial support for African farmers.
Attending the Rome conference in his new role as the chair of Agra, the Alliance for a Green Revolution in Africa, he said the African farmer was the only farmer in the world that still took all the risks, often operating without financial support, expertise or safety nets.
Pledges of aid continued at the summit on Wednesday.
The World Food Programme announced an extra $1.2bn in assistance for 60 of the hardest hit nations.
Food and Agriculture Organisation Director General Jacques Diouf announced that the Islamic Development Bank would give $1.5bn (£766m) in aid to farmers in the poorest countries.
The FAO is hosting the conference, which ends on Thursday.