TORONTO -- Ontario school principals say their staff lack the necessary medical and professional training to deal with autistic children who could be spending more time in classrooms due to recent changes to government funding for therapy.

In a joint letter to Education Minister Lisa Thompson, three associations representing principals at Ontario's English, Catholic and French boards, said the changes announced last month will mean many students will be spending less time in therapy with trained professionals.

The groups said that if the necessary resources aren't made available to schools to trains staff and accommodate the students' needs by April 1, the government should delay the program changes.

"Due to the limited information available from the Ministry of Children, Community and Social Services since the policy changes were announced, the education community needs direction on these critical issues before the changes take effect so that we can ensure we have the necessary resources to provide a safe, appropriate, meaningful, engaging and well-supervised learning environment in every school," the groups said.

The new autism program gives families up to $140,000 to pay for treatment -- a maximum available only to the lowest income families whose child is in treatment from ages two to 18. The funding is also subject to annual caps of $20,000 a year until a child turns six, and $5,000 a year after that to age 18.

But families say intensive therapy can cost up to $80,000 per year.

The government has said the goal of the new program is to clear a backlog of 23,000 children waiting for treatment, but many of those on the list say they'd rather wait for full funding.

Thompson said she is consulting with Ontario's principals on the autism program changes.

"We are moving forward very methodically to ensure that every voice is heard because on behalf of the students of Ontario we have a mess to clean up," she said.

Meanwhile, the president of a regional autism service provider said in a statement Tuesday the agency is concerned the changes will impact its ability to serve clients.

"Many parents are telling us that these changes will be very difficult for them, and for their children, and we believe the new program will have significant limitations in terms of its ability to support the best possible clinical outcomes for children and youth with ASD," said Cathy Paul, of Kinark Child and Family Services.

Social Services Minister Lisa MacLeod's office said in a statement that over the next 18 months four times as many children will receive support through the new program.

"We trust that providers will continue to provide quality care to meet the needs of the influx of children and youth seeking autism services and supports," the statement said.