The report, compiled by the FAO and WFP, said the increase was a result of high food prices, and lower incomes and lost jobs, as well as a decline in foreign aid and investment in poor countries.
"This loss of income is compounded by food prices that are still relatively high in the local markets of many poor countries," the FAO said.
High food price
The report found the Asia-Pacific region to have the largest undernourished population, followed by Sub-Saharan Africa, Latin America, the Middle East
and North Africa.
Around 15 million people suffer from hunger in the developed world.
Diouf said that agriculture had not been given priority in the fight against hunger, with only 3.8 per cent of aid from donor countries contributing to food production in 2006, compared to 17 per cent in 1980.
He told Associated Press that inflated food prices in developing nations, which sparked riots in more than 60 countries, have now stabilised, but still remain comparatively high.
But he added world leaders were beginning to understand how crucial investment in agriculture is, pointing to the $20bn pledged by Group of Eight nations to help farmers produce more food.
The report comes two days ahead of World Food Day, which begins a week of talks among some 300 experts focusing on feeding the world in 2050, when the UN forecasts a global population of 9.1 billion.