A demand and supply review by Grant Thornton for the Education Department found Brimbank and Wyndham have more than half of the west's students with autism receiving Program for Students with Disabilities (PSD) support.

But few of the students have the benefit of local support services.

The review was prepared last April but was released only last week after a freedom of information request by Western Metropolitan Greens MP Colleen Hartland.

The review noted that autism was the fastest-growing disability in the state, up 21 per cent in the past four years.

Students funded for autism under the PSD more than doubled, from 1946 in 2006 to 4103 in 2010.

"The majority of students supported under the [autism] category of the PSD are in their primary years, which will place increased pressure on secondary mainstream and general specialist schools to provide for this cohort over the next two years," the report found.

Autism Angels president Dina Tamburro said the findings came as no surprise to parents in the area.

The Taylors Lakes mother said schools were not meeting the growing need for teachers and aides to be trained in supporting students with autism.

The number of students with autism enrolling in mainstream schools has rocketed, from 154 in 2006 to 429 in 2010.

Ms Tamburro said it was important for parents to have the choice of mainstream or specialist schools, but the west still has no specialist school beyond grade 3.

"We're supposed to have this prep to year 12 school in Laverton, but there's still no answer about when that will be. They're not telling us the full story."

Western Metropolitan Liberal MP Bernie Finn said the government remained committed to the Laverton school before the next election.

But his priority is to see the integrated disability education and awareness program running at Moomba Park Primary School in Fawkner rolled out across existing schools.

Mr Finn cautioned that community expectations must be balanced against budgetary demands.