Birmingham's academies and their sponsors will not be educational islands but spread resources across schools, officials claimed.

The city council has defended controversial plans to create seven "independent state" city academies in Birmingham.

The plans have been vigorously opposed by the National Union of Teachers which claimed private sponsors would be able to take over public assets.

It also believes they will allow organisations not involved with education to gain control over pupils by donating the required £2 million in sponsorship, and the local education authority will lose control over admissions, affecting allocation of pupils across the city.

The city council has revealed more details of its proposals which it claims differ radically from the Government model, created to replace failing schools.

It stressed the authority would retain control over admissions and each academy will have several sponsors to prevent any one gaining too much control.

Education chiefs claim sponsors would "work equally" with six schools, including the academy, in an area network. It is proposed there will be six area networks, one of which will have two academies and the others one each.

A consortia of three or four businesses and community partners will be created for each sector. Their combined £2 million contribution will be spent on "specialist facilities or services" that will be available to all schools they support.

The authority says the academies would operate under the same selection and admission policy of other secondaries.

Staff terms and condit ions would remain unchanged on a school's transition to an academy.

In a report, council assistant director of school effectiveness Sylvia McNamara says: "The model for Birmingham academies is one of collaboration. They will remain part of their area network and will work to the strategy as set by the area networks in line with the Birmingham education vision."

The Birmingham branch of the NUT has criticised what it believes is a lack of public knowledge or consultation.

It held a public meeting last week to discuss the issues and has conducted leaflet drops around schools that will be affected by the proposals.

Bill Anderson, deputy general secretary of the Birmingham NUT, said: "The proposals have been made behind closed doors by a small group of people. This issue must be brought to the attention of Birmingham people for open debate."