The fight to ensure that girls in the developing world have access to education is being hampered by increasing privatisation of schools, a damning new report claims.

Low-fee private schools - seen by supporters as an effective way of educating the poor - are still too expensive for many families, who tend to prioritise education for their sons, the report says. It highlights research from charity Oxfam showing that the cost of low-fee education for an average-sized family in Pakistan would be 127 per cent of household income. In Malawi, it would cost families a third of their income.

The report raises concerns that in some countries the private education sector is unregulated, leading to schools being unaccountable if girls are sexually assaulted by teachers or staff.

The findings have been disputed by proponents of low-cost private schools, who claim they provide a cheap and effective method of mass education. Families who can’t afford fees can be supported by state- or donor-funded vouchers, they argue.

James Tooley, an academic and advocate of privatised education, criticised the report as “a rehash of old ideological ideas” that failed to suggest solutions for improving girls’ education.

But the paper - drawn up by 13 organisations supporting girls’ education, including the Education International global federation of teaching unions - calls for states to take on the responsibility of providing schooling themselves.

The report says: “In order for women and girls to be able to realise their right to education, as well as their rights to non-discrimination and equality more broadly, it is imperative that education be seen as a public good, and not as a commodity.

“The negative consequences which are borne when education is privatised, such as systemic discrimination against girls when education becomes marketised, cannot be adequately redressed through increased regulation of private actors alone.”

The United Nations estimates that 123 million people aged 15 to 24 lack basic reading and writing skills, and 61 per cent of these are young women and girls.

Lucy McKernan, UN liaison with the Global Initiative for Economic, Social and Cultural Rights, one of the organisations that delivered the report to the UN Committee on the Elimination of Discrimination against Women, said that for poor families even low fees were a “massive disincentive” to educating girls.

Keith Lewin, professor of international education and development at Sussex University, said charging for education was “an outrage”. Poor boys also missed out because of fee-charging, he added, and using state funding to pay private organisations to provide education was “risky” because of a lack of transparency and regulation. He stressed that a number of poor countries, such as Sri Lanka and Vietnam, were improving their education systems effectively through state-funded schools.

But Mr Tooley, co-founder of the low-cost Omega Schools chain in Ghana claimed that the report was selective in its use of existing research, which actually painted a more nuanced picture. The evidence that private schools discriminated against girls was not as strong as the report suggested, he said, and in West Africa it was “not true at all”. The authors had also ignored research showing that the quality of teaching and outcomes in private schools tended to be better, he added.

“A conclusion which went closer to the evidence should have been: give poor girls and their families vouchers or cash transfers so they can access low-cost private schools to the same degree as boys, in those few countries where this is not already true,” he said. “This.report simply sets out to deprive girls and their families of real choices in the interests of a narrow ideology.”