Schools are facing costs that could run to millions of pounds because of new legislation that could see them "picking up the bill" for the extra services needed by their SEN pupils, The TES has learnt.
The Equalities Act, which was passed last year, makes headteachers liable for funding more equipment and support staff than previously.
These could add up to tens of thousands of pounds for each child, particularly those with exceptional and complex needs.
Local authorities have traditionally met these costs through the statementing system and schools were not under obligation to meet any shortfall.
But thousands of heads will now have a legal "duty" to pay for IT, building work and teaching support for SEN children who want to come to their school.
Experts have warned that the act leaves schools open to legal action from parents disappointed with SEN provision for their children.
The act came into force last year, but the sections which cover disability aids and services are yet to take effect because Department for Education officials are preparing guidance on the change.
Heads' union the NAHT has warned members that local authorities may not include all the "aids and services" needed, leaving schools to "pick up the tab".
David Bateson, chairman of the Federation of Leaders in Special Education and principal of Ash Field School and Assistive Technology Assessment Centre in Leicester, said the cost of aids could run into "tens of thousands of pounds".
"This is a very sensitive issue because schools want to provide for all and to be fair," Mr Bateson said.
"But this legislation means parents who don't think their child has been given the same treatment as other children can hold teachers liable.
"Sadly, I think there will be test cases. Heads will join together to form mutual assurance networks, which will come to their aid when they have children with exceptional and complex needs. It's clear we won't get additional resources."
Brian Lightman, general secretary of the Association of School and College Leaders (ASCL), said: "This change will have serious resource implications if schools are not properly funded."
Eddy Jackson, head of Highfurlong special school in Blackpool, said teachers should do their best to make sure "all children have equal rights".
"This is not a Third World country," Mr Jackson said. "We've got to fight this battle and give them the same opportunities as all children.
"But as heads, we are now in survival mode. To comply with this duty, we will have to work jointly and share resources."
Mark Blois, a lawyer with Browne Jacobson, said: "Schools do not know when it will be considered `reasonable' to provide aids and services, and it could involve considerable expenditure."
THE EQUALITIES ACT: What it means .
- Pupils should not suffer discrimination for their sex, race, disability, religion or belief and sexual orientation.
- Anti-bullying policies must be in place, and schools must not discriminate against pupils who are pregnant or undergoing gender reassignment.
- All "reasonable adjustments" must be made to ensure that disabled pupils do not suffer discrimination.
- New "positive action provisions" will allow positive discrimination in favour of some pupils; for example, by providing catch-up classes for Roma children.
- Original headline: Extra cost to schools for SEN support could run to millions