Former foster children are demanding a Royal Commission of Inquiry into historical abuses, saying the proposed ministerial inquiry could easily turn into a cover up.
The new government has pledged to set up an inquiry into the abuse of children in state care.
But a spokeswoman for the Care Leavers Australasia Network, Netta Christian, said survivors of abuse could feel fobbed-off by a ministerial inquiry, because it would be controlled and overseen by politicians.
"What we want is a Royal Commission and that's non-negotiable," she said.
New Zealand was the only Commonwealth country that had not yet held a Royal Commission of Inquiry into abuse, she said.
"The inquiry must be fully transparent, with the power to make referrals to police, and order reparations for victims and apologies from the state.
"It must be able to compel witnesses and access unredacted documents, it must not have cut-off dates and it must deal with structural changes to our systems."
New Zealand should not make the same mistake as Australia and limit the inquiry to sexual abuse, which excluded many survivors, she said.
The inquiry should cover all forms of "out of home care" - including homes run by churches and charities as well as the state - and all forms of abuse.
In July, the National-led government rejected a petition signed by 12,000 people calling for an independent inquiry into state care abuse.