School "choice", market-based approaches to school improvement systems are on the rise in the majority of countries in the developing world, according to the Organisation for Economic Co-operation and Development (OECD).
Its annual Education at a Glance report has found that more than half of its 39 member and partner countries have increased freedoms in state school choice in the past 25 years.
The study also says that financial incentives such as voucher systems and scholarships are "an important means of promoting school choice".
A third of countries had used vouchers or scholarships to help families choose state-funded schools, but less than a fifth had schemes of this type covering privately funded independent schools.
New autonomous state schools had been created in 12 OECD countries, ten had introduced new funding schemes to promote school choice and six had expanded opportunities for home schooling.
Andreas Schleicher, head of the OECD's indicators and analysis division, said: "We want to look at whether these kind of changes towards a more open schools system have an impact.
"Despite the trend towards more choice and parental difference the picture is quite different across the countries."
The study shows the UK has one of the biggest private school sectors and that the difference between class sizes in the country's state and independent primaries is the biggest in the OECD at 25.7 pupils compared with 13.5.
John Bangs, London University Institute of Education visiting professor, claimed the new section in the report was had more to do with political pressure from right wing OECD governments than any educational rationale.
UK PRIMARIES SPEND LEAST
British primaries spend a smaller proportion of their budgets on teachers' pay than any other developed country, according to the Organisation for Economic Co-operation and Development (OECD).
Just 45.2 per cent of resources went on salaries compared with 78.1 per cent in Irish primaries and 85.4 in Mexico in 2007, it said this week.
But UK and Denmark primaries spent 28 per cent of resources on support staff pay, more than those in any other OECD country.
The average primary starting salary in England in 2008 was #163;30,534; above the OECD average of #163;28,949.
Across the OECD, secondary pay per teaching hour was 39 per cent higher than in primaries. But in England, primary hourly teaching rates were 9 per cent higher.