The claim came as it was revealed that several of Prime Minister Tony Blair's cherished new academies were being forced to turn away thousands of disappointed parents.
John Dunford, general secretary of the Secondary Heads Association, warned: "Parental choice is the wrong word. As soon as applications exceed the number of places, it becomes not a question of the parent choosing the school but the school choosing the parent."
Fears are growing that the schools' popularity will lead to a two-tier system - with better-off parents snapping up places by exploiting admissions procedures and buying homes in the catchment area.
Several schools are now resorting to radical new admissions procedures in an attempt to avoid social segregation. One, the Haberdashers' Aske's Hatcham College Academy in Lewisham, south London, has adopted a new lottery-style system - where places are held back and then distributed on a random basis to applicants.
The school is one of the most popular in the country with 2,523 parents chasing just 208 places this year.
The scheme may well be replicated nationwide as parents' leaders last night called for all oversubscribed schools to adopt it.
Margaret Morrissey, spokeswoman for the National Confederation of Parent Teacher Associations, said: "If you have 2,523 parents chasing 208, you have 2,315 disappointed parents at the end of the day. What choice do they have?" Ministers have studied the plan and given it the green light. It is included in a new code of practice on school admissions as a fair and acceptable way of determining applications.
Hatcham College is not alone among the academies in being forced to turn away disappointed parents. At the Lambeth Academy, 1,257 parents are fighting for 180 places while at the City of London a further 1,000 are also after 180 places. According to the Department for Education and Skills, all 17 academies in the first tranche set up are over-subscribed.
Ruth Kelly, the Education Secretary, speaking at the Labour party conference, admitted yesterday the Government would have to take action over school admissions to avoid wealthier parents going to the head of the queue. "For too long access to some schools was open only to those who could afford to buy an expensive house next to a good school while the rest were told to accept what they were given," she said. "There was nothing fair about that approach."
Her comments came as the academies programme - the Government is committed to establishing 200 by the end of the decade - came under fire from former Labour Education Secretary Estelle Morris.
"If we stop thinking about every school being a good school and just concentrate of 200 city academies over the next five years, I think we will have wasted an opportunity," she told the BBC Radio Four Today programme. "Surely the real question is how do we raise standards in every school? And nobody has yet explained how having 18 or even 200 city academies, or more parental choice, will do that."
The Haberdashers' Aske's scheme is one of many devised by the new academies - all of which are privately sponsored and have an average of £25m worth of government cash aid for new buildings - to overcome social segregation. An academy in Walsall - sponsored jointly by the Mercers Company and Thomas Telford, the comprehensive which constantly tops government exam league tables - has introduced a "doughnut" system, under which the school's catchment area is divided into an inner and outer ring, with spaces reserved in each for applicants so children from a range of different social areas are admitted to the school.
In neighbouring Sandwell, another academy has identified six "centroid" points - ie different suburbs - and takes a proportion of pupils from each of them.
Martin Rogers, head of The Education Network, a think-tank offering advice to local education authorities, said: "It's not surprising if the Government is splashing out £25m on one school and nothing like that on the one down the road that parents say 'we'll give it a go'."
A real lottery, not a postcode lottery: Haberdashers' Aske's Hatcham College, Lewisham
Haberdashers' Aske's Hatcham College in Lewisham, south London, is one of the most popular schools in the country, with 2,500 parents chasing just 208 places.
As a result, the college, which became an academy at the beginning of this month, is to adopt a lottery-style admissions system to avoid social segregation at the school.
The "random allocation" scheme - similar to lotteries already run by some oversubscribed schools in the US - is seen as a way of bringing a halt to the process of wealthier parents buying up properties near a popular school. This would have enabled them to snap up all the places on offer - as often happens when proximity to the school is used as a major means of allocating places.
Ministers have given their blessing to the scheme, whichcould be adopted at schools around the country. It has also won support from those sceptical about the academies programme - including parents' leaders - who believe it should be adopted in all popular, oversubscribed schools.
Martin Rogers, of The Education Network - a think-tank advising local education authorities, said the scheme offered "a solution to the social segregation arising from soaring house prices" which were "shrinking intake areas around popular schools".
The Schools Adjudicator - responsible for hearing appeals against schools' admissions systems - said recently of random allocation: "It provides schools with a mix of children from families who live in different areas of towns."
The names of the successful are selected randomly by an outside independent body.