And the teachers surveyed believe the rate is three times higher in primary than secondary schools.

The poll by the National Autistic Society (NAS) also suggests three-quarters of the profession feel there is not enough training offered to teachers in how to deal with autistic needs.

The findings, published on the eve of Autism Awareness Week, echo wider public fears that autism cases are on the rise.

It is still unclear whether the rise in the numbers of children being identified with autistic spectrum disorder is due to greater awareness or a real rise in numbers

Dept for Education and Skills

Concern over suggestions it was linked to the MMR combined measles, mumps and rubella injection have resulted in declining take-up of the jab, despite government reassurance.

The NAS report suggests teachers believe one in 86 primary schoolchildren in England and Wales is autistic.

The number in Scotland was much lower - one in 121.

In special schools, as many as one child in three has particular needs related to autism, the society says.

Autism is an umbrella term for a large number of similar "developmental disorders".

There are an estimated 500,000 people in the UK suffering from autism, which can cause difficulties in talking and relating to other people, depending on the severity.

Training call

NAS director of policy and public affairs Judith Barnard said: "It is clear from these findings that central government and local authorities must invest more to meet the needs of children with autism spectrum disorders in all schools.

"These children desperately need the support of relevant professionals who in turn require adequate training in order to understand autism."

Autism Report

1 in 86 pupils diagnosed in Eng & Wales 1 in 121 diagnosed in Scotland NAS figures Primary school age

A spokesman for the Department for Education and Skills said �25m was being invested in the next three years into improved training so the special educational needs of a child would be identified earlier.

He said: "It is still unclear whether the rise in the numbers of children being identified with autistic spectrum disorder is due to greater awareness or a real rise in numbers.

"Either way, greater identification provides the opportunity for the early, focused interventions which benefit these children."

Autism Awareness Week runs from Monday, 14 May to Sunday, 20 May.