Justice Peter McClellan will use a speech to the Association of Children's Welfare Agencies in Sydney to call for allegations made by children to be appropriately heard and investigated, regardless of where they originate, and without institutions or their leaders being able to diminish the preparedness of adults to act.

The speech comes days after human rights groups called for the Royal Commission into Institutional Responses to Child Sexual Abuse to investigate Australia's immigration detention centre on Nauru amid leaked reports of sexual violence, abuse and self-harm by refugees and asylum seekers detained at the facility.

The commission says investigating alleged child abuse on Nauru or Manus Island is outside its jurisdictional powers, and the speech does not cite immigration detention abuse allegations.

Justice McClellan will tell the conference the commission has heard from more than 5500 survivors of abuse in Australia in private sessions so far, and has referred more than 1600 allegations to police and other authorities.

Since the commission was established in 2013, more than 60 prosecutions have commenced as a result of the referrals.

"A picture is emerging for us that although sexual abuse of children is not confined in time – it is happening today – there has been a time in Australian history when the conjunction of prevailing social attitudes to children and an unquestioning respect for authority of institutions by adults coalesced to create the high-risk environment in which thousands of children were abused," Justice McClellan will tell the conference.

"The societal norm that "children should be seen but not heard", which prevailed for unknown decades, provided the opportunity for some adults to abuse the power which their relationship with the child gave them.

"When the required silence of the child was accompanied by an unquestioning belief by adults in the integrity of the carer for the child, be they youth worker, teacher, residential supervisor or cleric, the power imbalance was entrenched to the inevitable detriment of many children."

Justice McClellan will argue a child's complaint must be given an appropriate response, regardless of how it is received.

"Whatever the nature of the institution and however its members are respected by the community, we must all accept that there may be members of trusted institutions who fail in their duty towards children.

"The power of the institution must never again be allowed to silence a child or diminish the preparedness or capacity of adults to act to protect children."

The commission has held 60 private sessions with people aged under 25.

The Australian Council for International Development, Human Rights Law Centre and Australian Council of Social Services released legal advice on Friday asserting the commission does have the power to examine Nauru detention.

Human Rights Commission president Gillian Triggs called for the commission to be extended to examine how Australia has managed allegations from Nauru.

The commission, due to deliver its final report by December 2017, will close applications for private hearings next month.