An early intervention program for very young victims of sexual abuse is needed to avoid chronic adult mental health illness across Australia, a royal commission has heard.

Wayne Chamley from Broken Rites, a support group for people abused in the Catholic Church, said on Wednesday a national redress scheme for abuse survivors should include an early intervention program for children between the ages of three and 12.

He was giving evidence at a royal commission hearing into how to compensate victims of childhood sexual abuse.

Dr Chamley said Broken Rites supported a national redress scheme but would like to see an early intervention scheme as well.

Despite the federal government rejecting a national redress scheme, Dr Chamley said his group and others would continue to campaign for one - including going to the UN.

He said a high proportion of people who came to Headspace, a mental health program for people aged 14-25, were victims of childhood sexual abuse.

Broken Rites would like to see the program expanded for younger children.

"So this is a major public health problem and we can begin to work to diminish its impact and the key is to get an early intervention program in place nationally, which is directed at the childhood group."

Dr Chamley said Broken Rites supported a national redress scheme with governments and institutions contributing funds but having no part in administration.

He said it was hard to measure the impact of abuse but he would like the commission to acknowledge that because of childhood abuse, many men had lived lonely lives.

"They have lived as loners for all of their life with only drinking mates, never involved in a relationship with a person of the same sex or the other sex; never knowing what it is to have the joy and responsibility of raising family and those sorts of things," he said.

Tragically there were also many who took their own lives, he said.