The changes could mean councils can no longer force schools to create new places to deal with demand – with 336,000 more needed by 2024 – the Local Government Association (LGA) claimed.
The association, which represents more than 370 councils in England and Wales, fears such powers will flow away from councils – organisations with local knowledge – to central government.
The body highlights how in its Educational Excellence Everywhere White Paper, the Government states councils will retain the responsibility for meeting demand.
But the LGA has called on the Government to explain exactly how town halls, which according to the association have created 300,000 extra primary places since 2010, will be able to continue doing its job in future.
Academies are able to set their own pupil intake numbers, with no requirement to consider local need, the organisation claimed, adding that in some areas finding suitable sponsors is already proving a challenge.
An LGA spokesman said an additional 336,000 primary school places will be needed by 2024. While councils have been able to boost places, this has usually been achieved within the 85 per cent of primary schools that are council-maintained, by making difficult decisions such as by converting non-classroom areas, increasing class sizes and diverting money away from vital school repair programmes to create more spaces.
Under a fully academised system, sponsors will be invited to submit proposals and a final decision on a new school will be made by central government, rather than the local council, 'despite its unique understanding of local needs', said the spokesman.
The LGA has also called for clarification of how vulnerable children will be accommodated within the new system. For example, a council can currently force a school to accept a child with a formal statement of special needs, but not otherwise.
Councillor Roy Perry, chairman of the LGA’s Children and Young People Board, said, 'Local councils have been working hard to not only fulfil their duty to ensure every child has a school place, but to make sure as many as possible get their first choice – it isn’t just about a place for a child, but the right place.
'If proposals within the Education White Paper go forward and all schools convert to academies, councils must be given powers to force schools to expand where this is in the best interests of new and existing pupils. Most academies will be keen to work with their local authorities, but in the minority of situations where this isn’t the case, appropriate powers are vital to ensure all children get a suitable place.
'Councils will also need a greater role in judging and approving applications for new schools to make sure they’re appropriate for communities, and will need to be able to place vulnerable children in the schools that can offer them the best support.'
Capital shortfall in school places
Meanwhile, mayoral candidate Sadiq Khan pledged to work to 'fix the school places crisis' in London as new official statistics suggest Government cuts will impact construction.
The Labour candidate said cash spent on building new schools countrywide would halve, from £323 million in 2015 to just £141 million in 2018, with some London boroughs set to receive no funding at all.
Mr Khan's office said the capital has the biggest shortfall of school places anywhere in the UK and London councils predict the capital will need 131,000 more places between 2015 and 2020.
The funding drop could mean more children will miss out on attending a school of their choice and the increasing overcrowding of classrooms will continue.
Mr Khan pledged to convene a working group of London councils to plan school places across the city – with the aim of ensuring new schools are built where they are most needed.
He said, 'My daughters are teenagers and I remember only too well the panic as we waited to hear whether they had been got a place at the school of their choice.
'Fewer children in London are getting their top choice because of the growing shortage of places.
'This massive Tory cut to funds to build new schools is hugely irresponsible – and will only make this crisis worse.
'This comes on top of their policies which have made it nigh on impossible for councils to target new school places where they’re most needed.
'As mayor, I’ll work with London’s boroughs and the Government to fix the school places crisis.'