The global financial crisis has deeply affected the aid to poor countries and billions of dollars is required to meet shortages.
Both institutions said that the world must return to sustainable growth to hope to reach global poverty and health targets.
UN Secretary General Ban Ki-moon said the economic "upheaval has caused further shortfalls on aid, trade and debt, and on affordable access to medicines and technology."
The impact has particularly hit Africa, according to a new UN report on the funding gap on reaching the Millennium Development Goals.
"Although official development assistance is at an all-time high, we are 20 billion dollars short on commitments made for this year," Ban said. "Africa accounts for 80 per cent of that gap, that means 16 billion dollars.
"It is particularly distressing that the place of greatest need is also the place that accounts for the lion?s share of the shortfall," he commented.
Ban declared that "taken as a whole, this report paints a picture that should motivate world leaders to act with urgency at next week?s summit" that will review the Millennium Development Goals.
A summit in 2000 set eight ambitious aims for 2015, including reducing extreme poverty in the world by half, cutting infant and maternal mortality, establishing universal primary education and halting the spread of AIDS and other diseases which kill millions each year.
About 140 heads of state and government will attend the New York summit from September 20-22 when they will be asked to make new commitments.
With five years left to go, experts doubt that any of the targets will be met. They say money and political will is now lacking.
The UN report, "The Global Partnership for Development at a Critical Juncture," predicted that Official Development Assistance (ODA) will rise from 120 billion dollars in 2009 to 126 billion this year but this will not meet the promises made by the Group of Eight nations at a 2005 summit at Gleneagles in Scotland.
The eight nations promised then that they would double their aid spending to 50 billion dollars a year by 2010 and double aid to Africa to 25 billion dollars. It also said the shortfall to Africa this year was 16 billion dollars.
The UN secretary general said that global trade has begun to recover. "But it is unclear whether we will see the type of trade growth we saw before the crisis -- and which we need again to create jobs and income opportunities."
IMF managing director Dominique Strauss-Kahn also said that reaching the Millennium goals depends on a return to global growth.
"Everything hinges on restoring balanced and sustainable global growth. This is the foundation upon which everything else is built. Growth is not enough, but certainly, without it all other efforts to achieve the Millennium Development Goals will be frustrated," he said in a statement.
The IMF said developing should investing in infrastructure and create a stronger business environment to create growth, and make their economies more resilient to shocks.
IMF first deputy managing director John Lipsky said in a speech in Washington that "years of progress appear to have been lost, and the positive momentum has been derailed. Most important, the lost growth means delayed prospects for poverty reduction."