Pauline Hanson is under fire for suggesting autistic children be removed from mainstream classrooms to stop other kids being held back.
The One Nation leader made the comments during debate on the federal government's proposed schools overhaul in the Senate on Wednesday.
Senator Hanson insisted parents and teachers had raised the matter with her.
Teachers were devoting much of their time to disabled children, to the detriment of other students in the classroom, she said.
Disabled and autistic children should be taught in special classrooms where they can be looked after and given special attention, she said.
"If it was one of my children I would love all the time given to them to give them those opportunities - but is it at the loss of our other kids?"
"It's no good saying 'We've got to allow these kids to feel good about themselves and we don't want to upset them and make them feel hurt', and I understand that.
"But we have to be realistic at times and consider the impact that is having on other children in that classroom."
Australia could not afford to hold kids back as students in other countries overtake them in the rankings, Senator Hanson said.
Opposition Leader Bill Shorten condemned the comments.
"Heartbreaking and upsetting for parents of children with autism to hear @PaulineHansonOz say their kids don't deserve the same opportunity," he tweeted.
He read to parliament an email he received from a parent in response to Senator Hanson's comments
"What the senator is saying is that our clever, funny, naughty, spunky kid doesn't deserve a good education," the letter said.
"That she doesn't deserve the same opportunities as other kids. That she is lesser. Not worthy. Not really one of us."
Crossbench senator Jacqui Lambie said she wanted disabled children in mainstream classrooms because it was great for all students, including those without disabilities.
"They learn compassion. They learn how to deal with these matters. It gives them coping mechanisms for the rest of their lives. Everybody wins out with this," she told parliament.
Autism Awareness Australia has slammed Senator Hanson's comments as "appalling, archaic and cruel".
Chief executive Nicole Rogerson described Senator Hanson as a "truly deplorable woman".
"@PaulineHansonOz is a disgrace. Dangerous, hurtful and archaic thinking," she tweeted.
"This is one of the most disgusting things a member of parliament could say."
