that it had broadly "stagnated" since then.
"This is what worries us," she said. "Some countries are victims of their own success; they have succeeded in [improving living conditions] but.it results in more demand for education. This is a reality we have to face."
Of the children not receiving a primary education in 2012, Unesco claimed that 43 per cent were "unlikely to ever enter school". Almost a quarter (23 per cent) did start school but had since left.
Ms Bokova defended the global emphasis on levels of school enrolment prompted by the United Nations Millennium Development Goals. But she said that it was now time to also focus on the quality of education received by young people in the developing world.
"I think it was the right approach and we should continue to focus on getting enrolment [up], but not only [that]," she said. "If we don't have a high-quality education, keeping children in school and having quality learning, we will replicate the current situation where young people don't complete school.
"It means a waste of $129 billion [pound;75 billion] which was spent on education but with no result whatsoever. That's why I say, if we continue pushing only for enrolment, if we do not have the right environment around schools or curricula or we don't have an incentive to keep children in schools, we will just replicate this same process.
"Money will be spent without results. Illiterate people will continue to replenish this army of 800 million illiterate people in the world. It is a vicious circle of poverty and conflict.replicating the same cycle of unsustainability."
However, Ms Bokova said she was "optimistic" for the future because of the increase in education aid announced in Brussels last month by the Global Partnership for Education, an organisation that works with donors to drive up educational standards in the world's poorest countries.
Education aid has fallen by 10 per cent since 2010, but the conference appeared to mark a dramatic reversal of this trend. Of the GPE's developing country partners, 27 nations pledged to spend a total of an additional $26 billion (pound;16 billion) on education in 2015-18.
Donor countries in the West pledged more than $2.1 billion - a 40 per cent increase on the GPE's last round of fundraising in 2011.
The UK remains the largest individual donor, committing pound;300 million with the proviso that other donors also increase their pledges. "We cannot do this alone," said international development minister Lynne Featherstone.
Ms Bokova said the pledges reflected global commitment to education. "During the [worldwide economic] crisis, donors have slowed down but I think they are coming back to education," she added.
Many countries had still not finalised their contributions to the GPE; Julia Gillard, chair of the body, said she was confident that it would hit its target for the next four years.
Alice Albright, the GPE's chief executive, said the money would "make a big dent in some of the major challenges in education". "This is far, far in excess of what we had estimated, and demonstrates superb leadership and commitment to education [by governments]," she added.