Sweden's free school movement has increased segregation, encouraged secrecy between schools and given unfair advantages to independents, one of the country's top union officials has said.
Ann-Christin Larsson, a senior officer at teaching union Lararforbundet, was speaking ahead of a parliamentary meeting last week organised by the Trades Union Congress.
The comments are particularly timely as the Conservative Party has based a substantial chunk of its school reform policy on Sweden's free school movement.
Speaking to The TES, Ms Larsson warned that England should avoid making the same mistakes as Sweden when it comes to pressing ahead with the academies programme.
"It was decided when independent schools (free schools) were created that there should be more competition between schools, that it would create more pedagogical renewal and would be more cost- effective," she said.
"But the schools have not created any new pedagogical ideas - when schools compete they tend to be more quiet with their ideas than before. The new schools have not been more cost-effective either; there have been huge planning problems so it becomes very costly."
Ms Larsson added: "Independent schools have also created more segregation. Pupils attending these schools are from better off, more educated families. It's because they are more informed and they know how to work the system better."
The rise in independent schools in Sweden directly correlates to the baby boom that took place in the country 20 years ago, she said. The schools were providing capacity for a growing pupil population, but student numbers are expected to drop and there will be surplus places in the future.
"At the moment, public schools have not really been affected, but most pupils entering upper secondary level want to go to schools in the centre of the city. This is where most of the independent schools are," Ms Larsson said. "So while public schools in city centres will attract pupils, those in the suburbs could suffer."
Lararforbundet has been campaigning for fairer regulations within the school system, and there is a new act making its way through the Swedish parliament that obliges independent schools to follow the national curriculum.
The Conservatives have pinned a great deal of hope on convincing the English public that the reforms that took place in Sweden, as well as in the United States and Canada, are fit for the education system here.
It is understood the party will reiterate President Barack Obama's support of the Swedish model in the US, positioning the Conservatives' policies in line with the popular president.
The party's schools spokesperson Michael Gove said: "It is striking that even the unions in Sweden don't want to get rid of free schools. Parents are happy with free schools and the academic evidence shows that they have driven up standards for all and reduced segregation.
"By letting new schools set up we are giving all parents - not just the rich - the opportunity to send their child to good schools with small class sizes and disciplined classrooms."