TORONTO - The self-described "Education Premier" isn't moving quickly enough to clear the growing backlog of autistic children waiting for a crucial but costly therapy, critics charged Tuesday.

The wait list of autistic children who are eligible to receive intensive behavioural intervention therapy, or IBI, reached 1,148 kids on March 31, up from 985 last year.

More than 1,400 children were already receiving IBI services as of March 31, according to newly released government figures.

The long waits have forced many parents to drain their savings and go into debt to pay for the therapy the province has promised to provide, said NDP critic Andrea Horwath.

The government is moving at such a "glacial pace" to get kids off the wait list that many parents are worried their children won't get the service they need in time, she added.

"They feel that their children are rotting on the vine," Horwath said.

"Those are the words that more than one group of parents used at a town hall meeting about a month ago. That's a frightening and horrifying thing for a parent to have to admit."

The wait list is getting longer because the province is putting more money into providing therapy for autistic children, said Premier Dalton McGuinty.

"We've tripled the funding in the last four years, we've doubled the number of children who are being served, and we're bringing therapy into the classroom for the first time," he said.

"So I think we're making some real progress, but obviously there's more to be done."

Teachers and support workers are being trained to provide applied behavioural analysis therapies in schools, said Education Minister Kathleen Wynne.

Some schools already have therapists to provide IBI, but not in regular classrooms because such one-on-one therapies work better in a separate space, she said.

Children and Youth Services Minister Deb Matthews said the province has moved "aggressively" to improve services for autistic children, such as funding summer camps.

While the government is working towards providing IBI in schools, it "won't happen overnight," she said.