By Alison Smith
BBC News education reporter at the NASUWT conference
City academies amount to the privatisation of state education in England and there should be a moratorium on them, teachers say.
The NASUWT want to keep the "public sector ethos" of education
The NASUWT union says academies undermine democratic accountability and may undermine staff pay and conditions.
The union says academies fail all six of the tests it has devised for private sector involvement in state education.
Delegates also opposed the creation of "trust schools" and any increase in private sector involvement in schools.
Teachers expressed concern that the creation of trust schools, proposed in the government's education bill, would lead to a denigration of their pay and working conditions.
Some said the bill was a re-hash of the Conservatives' policies in the late 1980s for the creation of grant maintained schools, which operated outside of local authority control.
But the Department for Education and Skills said academies were "making big strides in a very short space of time".
'Public service ethos'
Sue Rogers, from NASUWT's national executive, said the union wanted to preserve the "public service ethos" of education.
"We are committed to the idea that state education is a public service. That ethos is of caring and giving," she said.
The report also expresses concern that major national companies are seeking to promote their products to young people by supplying curriculum resources, with schools seizing upon opportunities to supplement income and the curriculum.
Ms Rogers said the union was concerned that city academies were not subject to the same terms on pay and conditions as the rest of the state sector.
Academies are state schools which are independently run and listed as charitable companies.
Private sponsors have to provide £2m but the capital and running costs are met by the state.
NASUWT General Secretary Chris Keates said there needed to be some accountability for the way taxpayers' money was spent.
She dismissed city academies as an "opaque system".
"Where's the openness? As in any state-funded school, shouldn't we have the accounts fully available for public scrutiny?"
She said there was a role for the private sector in education and it could bring ideas, but it should not be involved in the governance and management of schools.
Ms Keates said there was "huge fear that the private sector could become involved in the education system in a way which was not appropriate".
Support for the bill
But the NASUWT would not be joining the "kill the bill lobby" as the Education and Inspections Bill contained some welcome measures on discipline, she said.
In particular, giving head teachers the power to discipline pupils who behave badly or commit violent acts away from the school premises was a welcome clarification of their rights, she said.
A spokesman for the Department for Education and Skills said the government remained committed to academies.
"Academies are reinvigorating education in some of country's most economically and educationally disadvantaged areas, replacing schools which have failed their pupils for generations, he said.
"Academies are making big strides in a very short space of time, and we will not be distracted from giving some of the most disadvantaged children in the country the best possible education."
Private sector involvement
The NASUWT has devised the following six tests for private sector involvement in education:
Does it in any way compromise the national pay and conditions of teachers? Does it adversely affect equality of opportunity in the workplace, lead to discriminatory effects or undermine social cohesion? Does it result in problems for trade unions in terms of recognition and legitimate access in support of members? Does it prohibit democratic participation or undermine accountability? Does it lead to increased burdens on the public purse in the short or long term? Does it result in better standards of educational provision?