Prime Minister Bill English is refusing to commit to an inquiry into the historical abuse of children in state care facilities.

But Labour leader Andrew Little has told The Hui if his party becomes the Government, he will.

Human Rights Commissioner Dame Susan Devoy has called for an inquiry into the historical abuse of Māori children who were mistreated in state care.

Around 100,000 children were institutionalised between the 1970s and the 1980s. More than half were Māori, and Dame Susan believes it could be worst human rights breach in our country's history.

Many suffered, physical, mental and sexual abuse while in the care of the state.

The Māori Party, ACT and United Future are supporting calls for an inquiry into the abuse, but the Government isn't keen.

Mr English told Three's The Hui it's already known that the scale of the abuse was huge, but questions whether knowing the specifics will help.

"I think we do know what happened," he told host Mihingarangi Forbes.

"We may not know exactly the scale, [but] the scale of it has been sufficient to warrant now fundamental change to how system works."

Labour leader Andrew Little said the least the Government can do is commission an independent inquiry - and make its recommendations binding.

"Hear from people who have been hurt and harmed by the state, when the state's role was to protect them. It actually oughtn't be a difficult thing to do."

Mr Little compared it to the Treaty settlement process, saying it would be "uncomfortable" but ultimately put people "at peace".

"It shouldn't be beyond us in this day and age, looking back in our history and seeing things that were wrong, to step up and take responsibility.

"If we've done things in the past that have been so woefully wrong… we want to avoid that ever happening again."

The Government's listening service heard from more than 1000 people who were abused in state care. It has now closed, with Social Development Minister Anne Tolley saying last year most were after financial compensation and an apology - not an inquiry.

Mr English said there have been "too many small-scale restructurings, and not enough of a hard look at fundamentally how our care of these vulnerable children has been organised" in recent years, hence the Government's establishment of the Ministry for Vulnerable Children.

"We've committed now the time and energy and money to making changes that they have long thought should happen, and will if we do it well, protect children in the future from the same thing happening again."

Māori Party - a spanner in the works?

The Māori Party has threatened to walk away from the Government if it doesn't amend the legislation which establishes the Ministry for Vulnerable Children, saying current provisions mean the ministry can avoid rehoming children with family if they deem it to be too much work.

"Just because it's a Māori home doesn't make it an unsafe home, and that's where we want to make it explicit in the law," co-leader Marama Fox said in February.

Mr English is confident they'll come to an agreement, saying they have "intentions in common".

"We would like to see those issues resolved, and I think the intent is clear, and we have a common intent - that where possible, Māori children are able to be placed and looked after [by family].

"Where they have to be taken - because sometimes they do, to save the lives of these children - that ideally they are in some other way connected with their culture."

Mr Little is a little more sceptical of the Māori Party, saying after nine years partnering with National, things are no better for Māori.

"We've worked with Marama Fox before over the homelessness inquiry… She made the promise she would take that report and its recommendations to the highest levels of Government. It hasn't led to anything."

Newshub.