Most developing countries are discriminating against girls in their schooling system, according to a global report released in Delhi yesterday.
Meanwhile some developed countries including Britain and Sweden are failing to ensure equality of achievement by boys: too many male pupils do not finish secondary education.
The Education for All monitoring report, published by United Nations education body Unesco, found equal access to schooling for girls remains a distant prospect in 54 countries, including 16 in sub-Saharan Africa, as well as Pakistan and India.
"These results are a cause for deep concern," said Koichiro Matsuura, director-general of Unesco, "not only because inequality is a major infringement of fundamental human rights, but because it represents an important obstacle to social and economic development."
The lack of progress means 60 per cent of countries are likely to miss the international target set in 2000 of equal enrolment of girls and boys in primary school by 2005. Only one in three countries will reach the target by 2015.
The greatest number of girls out of school are in sub-Saharan Africa (23 millon) and south and west Asia (32.4m). In the latter region, which includes India, Pakistan, Bangladesh and Nepal, 21.3 m girls are out of school compared to 11.1m boys. But Arab nations and central and Eastern Europe - where 77 per cent of illiterate adults are women - have poor records on equality too.
At a London press conference, Christopher Colclough, the director of the Global Monitoring Report, said those countries that hadn't achieved education for all and gender parity were breaking international obligations and often their own laws.
He said there was a strong correlation between poverty, inequality and traditional customs. Girls were held back for many different reasons. These include boys being favoured when poor families have to choose which child to send to school because they can't afford fees or costs such as school meals and uniforms.
"Incentives need to be strongly targeted," he said. "Income support should be contingent on school attendance by girls in countries where child labour is predominant."
He said rich countries need to quadruple the level of aid for basic education to $7bn (pound;4.2bn) a year if free universal primary education is to be achieved by 2015.
UK international development minister Gareth Thomas said his department is spending pound;1bn between 2002 and 2007 on helping developing countries achieve education for all but urged developed nations to step up support.
"Unesco's report is an urgent warning to the international community that we must step up our efforts to ensure all girls and boys of school age receive a good quality education," he said.