Jong-Wook Lee, director general of the WHO, said: "These global health gaps are unacceptable. A world marked by such inequities is in very serious trouble." Fourteen countries in Africa now have higher child mortality rates than they did in 1990, the WHO says. Average life expectancy in Zambia, Zimbabwe and Angola is now under 40, a trend which the WHO calls a "major public health concern".

It adds: "It is here [in Africa], where scores of millions of people scrape a living from the dust of poverty, that the price of being poor can be most starkly seen.

"Almost an entire continent is being left behind." Life expectancy has fallen by 20 years in Botswana, Lesotho, Swaziland and Zimbabwe - countries where up to a third of the population is now HIV-positive. The life expectancy of Russians has also fallen over the past 10 years, as their country's health system has collapsed and the Aids epidemic hit millions of people. A boy born in Russia today can expect to live for just 58 years.

One in three people in developing countries now dies before the age of 60, adding to economic deprivation, as a generation has been in effect wiped out by Aids.

Only 5 per cent of people in the developing world who need life-saving antiretroviral drugs for HIV receive them, according to the report. In Africa, 5,000 adults and 1,000 children die every day as a result of HIV and Aids, while around 30 million people on the continent are infected with the virus. Aids is now the leading cause of death in adults aged 15 to 59.

More than a third of children in Africa are at higher risk of dying before they reach adulthood than 10 years ago. A woman in Africa is 250 times more likely to die in childbirth than someone in Britain.