The boy's parents have since removed him from the public school he was at last year, complaining to the NSW Department of Education that two teachers repeatedly humiliated their son over a period of three years.

The department has denied the claims, saying teachers tried their best to support the boy, who had a history of violence.

"The principal...refutes any allegation that such behaviour occurred, rather staff made every effort to assist the student in his studies," a department spokesman said.

He said teachers had held interviews with the boy's parents, employed a teacher's aide and used counsellors to help him.

The boy's parents sent an email to Education Minister Carmel Tebutt, released by Opposition education spokeswoman Jillian Skinner, saying that their son, who has Asperger's Syndrome, wanted to kill himself as a result of the bullying.

"It is heartbreaking to hear your son tell you he just wants to jump in front of a bus so he doesn't have to go through the torment anymore," the parents said in the email.