A campaign to block plans for seven Birmingham secondary schools to be turned into academies will step up this month with the launch of a major public meeting.

The event, organised by five unions forming the Anti-Academies Alliance, aims to galvanise opposition to the drive.

Under the controversial programme, Birmingham City Council plans to turn the seven secondaries into privately-sponsored institutions outside local authority control.

It represents the Government's solution to under-achievement, particularly in inner city areas and involves giving schools greater freedom under fresh leadership.

However, union leaders vigorously oppose state school assets being put in the hands of private sponsors.

They claim the move will create an imbalance within the educational landscape and pitch schools against each other.

Bill Anderson, deputy general secretary of the Birmingham branch of the National Union of Teachers, said: "The problem is you set up a perception that some schools are best. Grammar schools are best. City academies are better than bog standard comprehensive schools. So you are setting up some schools to fail.

"What we should be doing is pumping in resources based on need into all schools so you try and equalise the performance between all schools."

Under Birmingham's proposals, charity Ark will sponsor St Alban's CofE and Harborne Hill schools. Edutrust, another charity aimed at tackling educational inequality, will sponsor Heartlands High and Shenley Court.

Black Country property firm Richardsons Capital will sponsor Kings Norton High. Each backer will contribute up to £2 million towards the project and will also be supported by a consortium of additional sponsors. These are: BMW, Cadbury, the universities of Birmingham and Aston, accountants PricewaterhouseCoopers, Matthew Boulton College, the Islamic

Bank of Britain, Working Links, OVE Arup and University Hospital Birmingham.

A consultation period of up to a year is currently taking place in relation to the five announced academies.

Sponsors for two further academies at Sheldon Heath and College High are still being sought.

The public meeting is being organised by teaching unions the NUT, the NASUWT and the Association of Teachers and Lecturers together with the GMB and Unison. It will be held on September 27 in the Council House.

Nationally, the Government expects to have 130 academies open by September 2008.