But she said many children are being removed from other situations and devastated parents and families are facing long and usually unaffordable battles to get them back.
Hini claimed a lack of accountability has led to ministry social workers "making things up to suit themselves", often to try to justify action which had already taken place, sometimes "on no evidence at all".
"This is a timebomb," she said. "This Government, and the public, have to start learning what is really going on. They are being taken for a ride by the staff.
"There is a culture of dishonesty and bullying within the very department that is supposed to be addressing such issues."
Hini said she would particularly like to meet Minister for Children Tracey Martin, who revealed at Question Time in Parliament that the number of children placed in care by Oranga Tamariki had been increasing over the last nine months.
In the first year of the new ministry, which was formed on April 1 last year, 500 more children and young people had been placed with child protection services.
The minister said of the numbers, "this Government believes New Zealand has the potential to build a world-leading child protection service".
But Hini said the employment of an extra 160 social workers and finding of an extra 140 carers highlighted the plan is to remove more children from families, rather than work towards decreasing the numbers, at a time when the Government is looking at addressing the wrongs of separation of children from families in the past.
"They have lowered the threshold. Social workers will do anything to justify what they have done, and they get away with it," she said.