"We stand no chance of substantially reducing poverty, child mortality, HIV/AIDS and other diseases if we do not ensure that all girls and boys can exercise their right to a basic education," said Carol Bellamy, UNICEF's executive director.

As mothers, educated women are more likely to have healthy children, and more likely to ensure that their children, both boys and girls, complete school. But illiteracy and ignorance puts women at risk in knowing how to space children and protect them as well as themselves against disease.

"When a girl is without the knowledge and life skills that school can provide, there are immediate and long-term effects. She is exposed to many more risks than her educated counterparts and the consequences are bequeathed to the next generation," UNICEF said in the report.

In most industrialized countries as well as large parts of Latin America, there was a "reverse gender gap" with boys dropping out of school or getting low grades while girls did well in academic subjects, the study said.

But the opposite is true in much of Asia and particularly in sub-Saharan Africa, where 24 million girls did not go to school in 2002, an increase of 4 million since 1990, reflecting in part a sharp drop in foreign aid.

Somalia scored lowest at 11 percent when overall primary school enrollment was measured from 1996 to 2002. In the same period, Tajikistan, the Netherlands and Sweden, for example achieved 100 percent, while Saudi Arabia was at 58 percent.

The score for enrollment in the United States was 95 percent - the same as Vietnam.

Foreign aid, grants and contributions to education in poor countries, with a few exceptions, failed to make the type of investment in education that would enable girls to attend and complete school, the report said.

Bilateral aid to education in 2000 was $3.5 billion, 30 percent less than a decade earlier.

When parents have to pay for school, usually the boys get preference, or children are kept out entirely, UNICEF said. In September 2000, world leaders at a U.N.

Millennium summit agreed to a series of goals to reduce poverty around the world. One was parity for boys and girls in primary education by 2005, a goal few believe will be achieved.

Bellamy said the global preoccupation with security since the Sept. 11, 2001, attacks against the United States could result in curtailing future pledges of aid to poor nations.

But many countries are trying. Egypt for example, pledged to end the gender-gap by 2007 by creating at least 3,000 "girl-friendly" schools, the report said.