Chief Ombudsman Peter Boshier will conduct a wide-ranging investigation into Oranga Tamariki's handling of uplifting new-born babies from their families.
Boshier says there has been a "great deal of public concern" following an attempt by Oranga Tamariki to remove a week-old baby from its mother in Hawke's Bay hospital last month.
"No one is more vulnerable than a newborn baby. I think the public needs assurance that the right policies and processes are in place for their protection while at the same time safeguarding the rights of whānau," Boshier said.
"My investigation is focused on what a good system should look like. As an Officer of Parliament, I have unique investigative powers under the Ombudsmen Act to require all relevant information from Oranga Tamariki and others to get to the heart of things and form an independent view."
Boshier acknowledged that Oranga Tamariki was already doing its own internal investigation into the Hawke's Bay case, and the Children's Commissioner had launched a thematic review focused on Māori newborns.
"My investigation will provide a broader overview aimed at identifying best practice," he said.
"It is important my investigation looks into the circumstances faced by all newborns and their whānau."
Boshier says while others are looking into this, he's answerable to the whole of Parliament and is the only one who is truly independent.
Alarm over Hawke's Bay hospital uplift
Minister for Children Tracey Martin welcomed investigation, but defended the embattled organisation, saying she didn't believe the public had lost confidence.
"I am really pleased we've got the ombudsman coming out in this way today," she told reporters.
"[But] this is not black-and-white stuff. Our social workers are trying ... to protect these little children."
Green Party co-leader Marama Davidson said the inquiry added much-needed public accountability.
"There is a focus in his inquiry on best practice and I really welcome that. This needs to be solutions-based," she said.
"We need to change the practice so that trauma isn't created and prioritise keeping babies safely with their families."
Oranga Tamariki (the Ministry for Children) has come under fire over its uplift policy and how they disproportionately affect Māori after an attempted uplift last month of a young Māori mother's baby from Hawke's Bay Hospital.
Oranga Tamariki said Māori babies taken into state care within three months of birth increased from 129 in the year to June 2016 to 160 in each of the two years to last June.
Babies of all other ethnicities taken into state care increased only slightly in the same period, from 118 to 121.
The embattled ministry has also been forced to apologise after it was revealed an Oranga Tamariki social worker joked to a mother about getting bonuses for taking children into care. Three weeks later that mother's child was uplifted.
On Sunday, Martin announced an internal inquiry into its processes around the Hastings family's case at Hawke's Bay Hospital.
"I was particularly sorry to see the events that unfolded in the hospital that day," she said.
"Everybody in that room has been impacted negatively and we need to come back together and work together constructively, not just for this whanau but also for the whanau of the future and the whanau that are actually in the process now."
But activist group Hands Off Our Tamariki says the issue goes far deeper than the single case, and has collected nearly 15,000 signatures on a petition asking the Government to "stop stealing Māori children".
Prime Minister Jacinda Adern said on Monday it was a "big job" to eliminate unconscious bias against Māori in New Zealand.
Budget 2019 invested more money into early intervention, and Oranga Tamariki was working with iwi to prevent Māori children being taken into Oranga Tamariki care.
She said the new legislation for Oranga Tamariki, set to come into force on July 1, meant that every effort should be made for uplifted children to be kept in the wider family.