National Party leader Simon Bridges says the response to the Budget data breach saga reflects either "gross incompetence or dirty politics".
Last week, Treasury Secretary Gabriel Makhlouf said the Treasury had been systematically hacked only hours after the National Party revealed it had access to Budget information.
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The department said it had referred the issue to police on the advice of the National Cyber Security Centre (NCSC), which falls within the Government Communications Security Bureau (GCSB).
But Treasury later admitted that it hadn't been hacked and someone had only "exploited a feature in the website search tool" which "does not appear to be unlawful".
Bridges said the Treasury only made the admission after the National Party said it was preparing to announce how it came to have the Budget information.
"Treasury has known since Tuesday exactly what happened and they covered it up to cover their incompetence," Bridges said at the time.
It was also revealed on Friday that Treasury had been advised by the NCSC to refer the matter to police for assessment last Tuesday as the data breach, as described to the NCSC, did not appear to involve Treasury's network being compromised.
The NCSC's role is to protect systems from advanced cyber threats.
Bridges said the whole situation angered him.
"I was outraged at the time - we had a situation where [Treasury] said it was a hack, they had to know it wasn't a hack because... the security agency, GCSB, told them so, they still went to police," he told The AM Show on Wednesday.
"It was only when I was going to come out on Budget Day and say here is what actually happened, well they must have known they were rumbled, and they said 'okay, no hack'."
Bridges said heads needed to roll for what was "either gross incompetence or dirty politics", which he described as sitting on a lie "quite consciously".
"Makhlouf's position is clearly untenable. He went out and put out a statement, having been told by GCSB that there was no systematic hacking, that there was," Bridges said.
"There are so many questions that come from this? What was their basis for going to police, we know it wasn't that they thought there was a hack because GCSB told them so."
The National Party leader said his calls for resignations wasn't about him but about "showing the Government's incompetence".
"It's about highlighting a Budget that wasn't about wellbeing and it was about seeing how a Government performs under pressure, and I think we have all seen they don't perform too well."
He also questioned why there hadn't been any apology from Finance Minister Grant Robertson, Deputy Prime Minister Winston Peters, and Prime Minister Jacinda Ardern.
On Thursday, Bridges called for Robertson to resign after alleging the Finance Minister had implied the Budget information National had obtained was hacked material. Robertson denies making such an accusation.
Robertson and Prime Minister Jacinda Ardern have both also said the Finance Minister's statement was based on advice provided by the Treasury.
"What I think we need to make sure is absolutely clear here is that no one has made a direct accusation to the National Party," Ardern said last Wednesday.
The advice given to Robertson from Makhlouf is now under investigation by the States Services Commissioner.
"The investigation will establish the facts in relation to Mr Makhlouf's public statements about the causes of the unauthorised access; the advice he provided to his Minister at the time; his basis for making those statements and providing that advice; and the decision to refer the matter to the Police," a statement reads.
That comes on top of a separate inquiry into the hole in Treasury's website and how the information was obtained.
Bridges also took issue with Peters.
"He went out to the Press Gallery and he made quite clear in his words that he knew what happened, that it was illegal, and that I needed to go," Bridges said on Thursday.