A group representing Suffolk County Council and other authorities across the country has warned that spiralling fuel costs are going to hit school bus and taxi services described as a "lifeline" for pupils.
The County Councils Network (CCN), which speaks for all of the country's 23 county councils and 13 county unitary authorities, said there was "little wriggle room" in budgets that have already been agreed, with vital services set to be hit.
This could especially impact SEND pupils with special educational needs, who often rely on transport to get to school, the CCN said.
At the start of the current academic year in September, Suffolk County Council awarded the school bus contract to one of its own companies - Vertas.
This was after the council's existing contract with Suffolk Norse for 40 bus routes came to an end.
In Suffolk, Vertas transports more than 250 SEND students and around 1,000 mainstream students daily.
Keith Glazier, children's services spokesperson for the CCN, said: "Free school transport is a lifeline for many pupils, but local authorities have been placed in a difficult position owing fuel prices reaching record highs.
"Transport providers are understandably concerned they are paying much more than a year ago, but it means councils either pay the higher rates they are requesting or potentially see thousands of pupils unable to access free school transport, which is a statutory responsibility for local authorities."
He added: "With our budgets set for the coming year, there is little wriggle room for local authorities, except to reduce other vital services.
"The chancellor's announcements this week will help, but we need further targeted financial support for councils to get them - and transport providers - through this uncertain period and give families the peace of mind that their children's school transport will continue to run as normal."
Meanwhile, Suffolk parents can now opt-in for funded school travel for the 2022/23 year.
If parents have a child who is already receiving Suffolk County Council funded school travel, they must opt-in by the 31 May 2022 to continue to receive it.
Families of children starting secondary school in September 2022 will receive an e-mail by the end of march if they are eligible for Suffolk County Council funded school travel.
If parents have a child starting primary school in September 2022, they should not opt-in until they receive the offer of a school place.
If they are eligible for Suffolk County Council funded school travel they will be contacted by May 15.
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