Doubts cast over Swedish-style free schools
The Swedish model of free schools, lauded by the Conservatives, has not significantly improved pupils' academic achievement, a study suggests.
The research, published in Research in Public Policy, found the biggest beneficiaries tended to be pupils from educated, professional homes.
The Swedish model has influenced the government's free schools policy.
Education Secretary Michael Gove believes free schools will lead to higher standards in England's schools.
In Sweden, non-profit and for-profit organisations are able to set up and run schools which are publicly funded, but independent from government control.
In England, all schools have been invited to become academies, which would allow them to opt out of local authority control
Groups of parents and teachers, charities and businesses are also being encouraged to set up free schools.
'Close to zero'
The paper, published in Research in Public Policy, examined a range of research into Sweden's experience of free schools.
The study found the scheme was limited in predicting how similar reforms would work in England.
Report author Rebecca Allen from the Institute of Education found those who benefited most from these schools were those from more privileged homes.
"The impact on low-educated families and immigrants is close to zero," the report said.
It went on: "The researchers also find that the advantages that children educated in areas with free schools have by age 16 do not translate into greater educational success in later life.
"The evidence on the impact of the reforms suggests that, so far, Swedish pupils do not appear to be harmed by the competition from private schools, but the new schools have not yet transformed educational attainment in Sweden."
In an answer to a parliamentary question on the policy, Mr Gove said on Tuesday that all the evidence showed that more free schools meant higher standards.
"They help close the gap between the poorest and the wealthiest children," he added.
Rachel Wolf, director of the New Schools Network, which helps groups to set up schools, said the study did not cover "important studies" of charter schools in the United States.
"That research, including lottery studies at Harvard, Stanford and MIT, has shown that allowing properly regulated new schools can bring dramatic improvements in school standards, especially for schools for poorer children in poor areas."
It was announced last week that more than 700 groups have expressed an interest in setting up a school.