The United Nations Children's Fund (Unicef) survey emphasises the link between children's lack of education and ill-health, claiming a "direct correlation between years of schooling and child mortality rates".

The report, The State of the World's Children 1999, says that children in developing countries who do not receive an education are more likely to face ill-health and will be less likely to be able to sustain themselves and their families.

Education is linked to life expectancy, says report

"The consequences of illiteracy are profound - even potentially life threatening," says Carol Bellamy, Executive Director of Unicef.

Basic healthcare, employment opportunities and social progress depend upon literacy, without which children face a lifetime of deprivation.

In the longer-term, the report says that there are serious social consequences in allowing 150,000 million children to leave school before they reach secondary school age.

"On a society-wide scale, the denial of education harms the cause of democracy and social progress and by extension international peace and security," the report says.

For all these children to complete their education would cost an extra £7bn a year for a decade, which the survey says would be a tenth of global armaments expenditure, or less than is spent on cosmetics in the United States or ice cream in Europe.

The report also notes that the education of girls, who will later become mothers of their own children, is the "single most important factor in providing education to all children".

While an estimated 855 million adults remain illiterate, the report notes there has been a rapid expansion in information technology. "The tragedy is that these same technological advances have only deepened the gulf between rich and poor."

The report asserts that education is a "fundamental human right", which if denied has serious consequences on both individual and society.