Resource depletion and surging population growth are draining the net "savings" of the world's poorest countries and could cripple future generations, according to a new World Bank study.
It said a new measure of wealth - which goes beyond the traditional gross domestic product yardstick - showed many developing countries were sinking deeply into the red.
"Accounting for the actual value of natural resources, including resource depletion and population growth, shows that net savings per person are negative in the world's most impoverished countries, particularly in sub-Saharan Africa," it said.
Entitled "Where is the Wealth of Nations?", the study looks at resource extraction and other variables not commonly used.
"Current indicators used to guide development decisions - national accounts figures, such as Gross Domestic Product (GDP) - ignore depletion of resources and damage to the environment," the World Bank said in a statement.
"Where is the Wealth of Nations? ... offers new estimates of total wealth, including produced capital, natural resources, and the value of human skills and capabilities, which show that many of the poorest countries ... are not on a sustainable path."
The study offers a ranking of 118 countries, with Switzerland topping the list with wealth per capita of $648,241. At the bottom is Ethiopia at $1,965.
Also near the bottom is the Indian Ocean island of Madagascar, which has rapid population growth, rampant deforestation and is losing much of its soil through erosion.
Densely populated and ecologically stressed Burundi - also a powder-keg of ethnic conflict - is second from the bottom.
The study says natural capital - the value of minerals, energy, forests, pastureland, cropland and protected areas - is a much higher share of total wealth in low-income countries than produced capital at 26 percent compared with 16 percent.
Produced capital is defined as machinery, structures and urban land.
The study looks at "intangible capital", which it says is calculated as the difference between total wealth and the sum of produced and natural capital.
There are bright spots in the developing world where resource wealth is being saved rather than squandered.
"Mauritania has improved its development prospects through better management of fishery resources, while Botswana has successfully used diamond resources to finance the schooling, health care, and infrastructure which have supported its high rate of growth," says the World Bank.
"(A) sound combination of macroeconomic and natural resource management has permitted Botswana to avoid the 'resource curse' that has afflicted many oil producers," it says.
Many African economies are heavily dependent on resources and critics say the cash generated in boom times are often wasted, leaving little for the busts of the commodity cycle.