UPDATED 5.36pm The Waitangi Tribunal claims the Crown is breaching its obligations to the Treaty because it hasn’t slashed high reoffending rates for Maori.

LISTEN ABOVE: Corrections chief executive Ray Smith spoke to Larry Williams

The results from an inquiry are out from a claim lodged by retired senior probation officer Tom Hemopo.

The Tribunal said the difference in reoffending between Maori and non-Maori is undisputed, longstanding, and substantial.

At least 10,000 Maori children are likely to have a parent in prison.

Further, it claimed the Corrections Department has no specific plan or budget even though the Justice sector announced a broad target to reduce Maori reoffending.

The Tribunal wants Corrections to come up with a new plan with specific targets.

Corrections Chief Executive Ray Smith admitted the department's plan doesn't go to the depth the Tribunal has suggested.

However, Smith supported strengthening the plan, "to get some measurable targets in it so that we can that we're travelling in a good direction and making progress."

"I totally support that," Smith said. "That's the next step we're going to take."

Tom Hemopo welcomed the Tribunal's report: "I think it was a fair report because it went straight down the middle - it gave the department's side and there was positive things, and I have always acknowledged that," he said.

Prime Minister Bill English said more needed to be done, not just for Maori but all offenders. It was not acceptable that half of prisoners were Maori.

"The prison population itself is too high. That is why we are doing things like changing the way the Government cares for children in state care, because there is a fairly predictable track for some of them to prison 15, 20 years in the future."

English said in the past four years there had been "a big lift" in mental health, literacy, and drug and alcohol programmes for prisoners.

"We believe we have lifted the effort for all prisoners in the interests of the safety of the community."

Corrections Minister Louise Upston said the report highlighted some areas Corrections was already working on, including an accord with Kingitanga.

"It is a problem and a challenge for Government, but it has been a long-standing and complex issue for us to solve."

Maori Party co-leader Marama Fox said she was glad the report had been released, and there were serious problems with the justice system's "institutionalised racism".

"I think there are a number of recommendations that we can take seriously and bring in front of the Government," Fox said, adding she had scheduled a meeting with Upston.