An alarming drop in international education aid money means there is a "real danger" of primary participation levels tumbling across the globe, a major new report claims.
After more than a decade of widening educational access, the number of children enrolled in primary schools around the world rose from 120 million in 2000 to more than 178 million in 2011.
But new research by the Global Partnership for Education (GPE), which has distributed $3.7 billion (pound;2.27 billion) to assist educational programmes in the developing world over the past decade, claims that a drop in aid prompted by slow economic recovery could mean progress is "stalled or reversed" in the years to come.
The GPE's Results for Learning report reveals that, in 2011, international aid funding commitments for education "plunged" by 15.8 per cent - more than double the 6.3 per cent decline in aid funding across all sectors.
Unless more funding is found, the report warns that a global "crisis" in the developing world could be imminent. "Unfortunately, a real danger is emerging that the number of children who are out of school will rise in the near future," the report says. "After a decade of rapid progress, now is a critical time for education in GPE developing-country partners."
GPE chief executive Alice Albright added: "We are facing a learning crisis in developing countries and this crisis is aggravated by a sharp decline in international education financing.
"We need to focus on this crisis if we want to avoid that millions of children are left behind."
At the World Innovation Summit for Education in Qatar in October, former UK prime minister Gordon Brown - now the United Nations' special envoy for education - hit out at the international aid agencies that had slashed their education funding in recent years.
"That is unacceptable, in my view," he told delegates, adding that an extra $6 billion (pound;3.7 billion) needed to be raised in order to achieve the United Nations' Millennium Development Goal of free universal primary education by 2015.
The latest GPE report warns that the drop in international aid for education has been compounded by many countries switching their focus and investment from the primary to secondary sector. Domestic education funding could also be "at risk" in less prosperous nations, it adds.
"Our biggest challenge is to reach the most marginalised children and those living in fragile and conflict-affected countries," Ms Albright said. "Moving ahead and making more progress will require the collective and sustained mobilisation of the global education community."
John Rendel, chief executive of Promoting Equality in African Schools, a chain of 22 low-cost private schools across Uganda and Zambia, told TES that his organisation, part-funded by the two countries' governments, was feeling the pinch. Although public sector spending in Uganda had increased significantly since 2007, the proportion spent on schools had dropped, he said.
"I can completely understand why aid for education is sometimes less than it should be: education outcomes are much longer term than spending money on food or health," Mr Rendel said. "So much of the aid gets spent on salaries, and it's very easy for money to go missing (through corruption).
"But it's appalling, the small amount of money that gets spent on education aid. The potential return on the investment is massive."
The GPE's report, however, pays tribute to the progress made since the turn of the millennium. In its partner countries in the developing world, the average primary school completion rate in 2011 was 75 per cent, up from 58 per cent in 2000. In the same period, the overall proportion of out-of-school children fell from 39 per cent to 24 per cent.
There was also progress in improving access to education for girls, despite ongoing issues in countries such as Afghanistan, the Central African Republic and Chad. In 2011, 93 girls completed primary school for every 100 boys, a 10 per cent increase since 2000.
Fred van Leeuwen, general secretary of Education International, the global federation of teaching unions, said that the emergence of conservative governments and austerity policies after the financial crisis of 2008 had created "a perfect storm to adversely impact children in countries who had been promised funding if they increased domestic funding (which they did) and had a credible plan."
Huge pressure now needed to be exerted on governments to "keep their promise to invest in quality education for all," he said.