"We have seen the human toll the recent attacks wrought in the United States, with citizens from about 80 nations perishing in New York, Washington and Pennsylvania," said the Bank's president James Wolfensohn.
"But there is another human toll that is largely unseen and one that will be felt in all parts of the developing world, especially Africa."
The fight against childhood diseases and malnutrition will be hampered by an economic slowdown, the Bank said in its preliminary assessment of the economic consequences of the attacks.
"We estimate that tens of thousands more children will die worldwide and about 10 million more people are likely to be living below the poverty line of $1 a day because of the terrorist attacks," Mr Wolfensohn said.
"This is simply from loss of income. Many, many more people will be thrown into poverty if development strategies are disrupted," he added.
Economic growth
Ahead of the attacks, the Bank had already predicted that economic growth in the developing world would fall from 5.5% in 2000 to 2.9% this year before bouncing back to 4.1% in 2002.
This prediction has now been changed.
The Bank's revised growth forecast for the developing world is now lower at between 3.35% and 3.6% in 2002.
The downward revision was made "because the attacks will delay the rich countries' recovery into 2002", the Bank said.
Tourists and investors flee
Different groups of developing countries will be affected in different ways, explained Mr Wolfensohn.
"For the poorest countries that stall or fall into recession as a result of a decline in exports, tourism, commodity prices, or foreign investment, the number of people living below $1 a day will rise."
"In countries that experience positive but slower growth, fewer people will be able to climb out of poverty than otherwise would have been the case."
Most developing countries are expected to see foreign investment drying up, reflecting the way the world's leading banks are cutting back their emerging markets teams.
" The pattern established in the 1990s of private capital flows accounting for a much greater share of developing countries' financing needs is expected to be reversed in the near term as both equity and lending activities contract in lower risk countries," the Bank said.
Aid, trade and policy changes
"Several steps are crucial in sustaining the global fight against poverty in the wake of 11 September," the World Bank's chief economist Nicholas Stern said, advocating that the international community must:
"Policy responses have to be swift and somewhat bolder in rich and poor countries because of the heightened level of risk to the global economyżand they have to be vigilant because the uncertainties associated with future political and military events are unusually large," Mr Stern said.