Schools could be left out of pocket with no means of appeal after new powers were given to parents to complain about SEN education, experts have warned.
The office of the local government ombudsman is now able to investigate schools that "act unreasonably" and fail to offer the right support to SEN pupils.
It can demand more resources for children regardless of whether extra funds are made available by local authorities. It is also able to order that compensation be paid.
Ombudsmen already investigate SEN maladministration, and tribunals will continue to decide whether children should get statements.
But denial of a right of appeal to schools will leave local authorities and schools paying for the new powers "literally and figuratively", according to the Local Government Association (LGA).
"This will affect budgets and have a knock-on effect on all resources," said Daniel Mason, policy officer at the LGA.
"It could lead to `buck-passing', where the problem gets passed between schools and local authorities if neither has the money."
Concerns have also been raised that "pushy" parents could use their new rights inappropriately.
The changes have been made following Special Educational Needs Consortium chair Brian Lamb's inquiry into SEN provision last year, which said radical changes are needed to the way schools and local authorities deal with parents of children with SEN.
"I hope giving parents a proper voice will lead to a situation where schools are more ruthlessly focused on outcomes for SEN pupils," he told The TES.
Richard Rose, director of the Centre for Special Needs Education and Research at Northampton University, predicts that some parents will view the new powers as a "blunt instrument" to use against teachers in an "unsuitable way".
"It's important sufficient power is still given to the professional powers of teachers and there is still room for dialogue with them," he said.
Lorraine Petersen, chief executive of the National Association for Special Educational Needs, said the changes could help teachers because it will make local authorities act more effectively.
"Schools do their best, but often all the paperwork and changes they recommend don't get further than local authorities, which leaves teachers despondent," she said.
But John Bangs, NUT head of education, criticised the decision not to allow schools right of appeal.
"There are cases where teachers think provision is inadequate and want it improved but can't act, and some parents won't appeal themselves," he said.
"The Government has never faced up to the reality of educating children with SEN, and the actual cost of giving individual support while they are in mainstream education."
But the new rules, which came into effect this month, could reduce the red tape burden on schools. Mr Lamb recommends that they should have to submit less data on SEN pupils to the Government as a "trade off".