The United Nations says the AIDS epidemic has forced it to cut its long-term projection for the world's population by four-hundred-million.

A new UN report on population estimates that more than three-quarters of those infected live in sub-Saharan Africa.

It predicts that the region will see a dramatic decline in life expectancy -- in some countries by as much as twenty years.

Outside Africa, though, the report is more optimistic, predicting that in 2050 manypeople will live for one hundred years or more.

The UN says it expects the world's population to increase from five point nine to almost nine billion people by the middle of next century.

But the report says the growth rate is decreasing.