Prime Minister Jacinda Ardern is refusing to throw her full confidence behind the Treasury, after Budget information was obtained by the National Party.

But Minister of Regional Economic Development, and senior NZ First MP, Shane Jones said Finance Minister Grant Robertson should "hunt down" the person responsible, if it is discovered there had been a leak.

"If there is someone who is playing fast and loose with information that he [Robertson] is responsible for, he should get the taiaha (Maori weapon) out and lob their heads off."

The National Party this morning released information that they say will be in Thursday's Budget.


Just hours later, National released more information it claimed was from the Budget.

Bridges said the information was obtained by National since the release this morning of other Budget information.

And again, even later in the day, National released more information – this time revealing what it says was information on funding for a Mental Health and Wellbeing Commission, as well as funding for Treaty of Waitangi negotiations.

Robertson this morning confirmed that some of the numbers released by National were correct, but some of them were wrong.

Robertson said he "was just not going to get into" how much of the information was accurate.

Speaking to media before going into the House this afternoon, Ardern also would not detail just which figures were indeed correct.

"In the aftermath of the actual Budget being released, I will return to what has happened here."

But she was adamant that the numbers did not come from the Beehive – meaning she's sure it wasn't a Minister or their staff.


"We can rule out this having coming from the Beehive, or anyone within it. But in terms of more detail on that, we're going to leave that until after we have actually delivered the Budget."

But she had no such confidence in Treasury.

Asked if she had full confidence in the Treasury, Ardern said: "We will deal with all of the aftermath of this after we have put the Budget out."

The head of the Treasury, Gabriel Makhlouf, said a review will investigate how the National Party obtained Budget information ahead of its release and look into the "potential leak".

But speaking to media, Jones was less diplomatic than Ardern.

"It's just fake news and an attempt to create a diversionary narrative," he said when questioned about the numbers.

This is despite Robertson saying some of the numbers were correct.

"But if there has been a deliberate and malicious leak, then I recall that Sir Roger Douglas offered to resign over that," Jones said.

Asked if Robertson should do the same, Jones said Robertson should "find where that leak came from."

"Grant, he is our senior Treasurer, he should hunt down who has done this."

Although he suggested that the person responsible for a potential leak should "get ... their heads off," in his next breath he said he did not want to "worsen anyone's mental health – mistakes do happen, in fact, I represent them".