The Beehive was urged to stop Treasury boss Gabriel Makhlouf from issuing a statement saying it had been hacked last week, a report says.
The revelation follows last week's drama when the National Party released Budget 2019 information two days before the full details were due to be released.
It prompted Makhlouf to issue a statement at 8pm on May 28 - the day National released the information - saying Treasury had "sufficient evidence that indicates the material is a result of a systemic hack and is now subject to a police investigation".
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But on May 30 Treasury issued a statement to say it hadn't been hacked, not long before National leader Simon Bridges revealed a search tool on the Treasury website was used to uncover the Budget material.
Andrew Little, Minister for the Government Communications Security Bureau (GCSB), received a call from GCSB director-general Andrew Hampton before Treasury's "hack" statement went out, a report by NZME has alleged.
Little's office did not respond to Newshub's request on Friday for confirmation that the GCSB Minister had been contacted by Hampton ahead of the release of Treasury's initial statement.
National deputy leader Paula Bennett said Little should have immediately phoned the Finance Minister and the Prime Minister to give them the information.
Finance Minister Grant Robertson issued a statement after Makhlouf's initial statement in which he named the National Party and echoed the Treasury secretary's description of a "systemic hack".
When asked if Robertson had any knowledge about the GCSB contacting the Beehive to say Treasury wasn't hacked, a spokesperson for the Finance Minister told Newshub he knew nothing of the concerns before releasing his statement.
Bennett said: "The fact that Grant Robertson went ahead and released a statement implying National had been releasing hacked information shows he was out to smear the National Party.
"He now needs to be up front about what information he had before he released that statement."
Robertson's spokesperson said details are subject to an investigation by the State Services Commissioner, Peter Hughes. He's looking into the "adequacy of Treasury policies, systems and processes for managing Budget security".
Hughes is looking to determine whether the Finance Minister was misled by the Treasury secretary about how the Budget details were accessed by National.
Hughes told Newshub the focus of the investigation is to "establish the facts in relation to Mr Makhlouf's public statements about the causes of the unauthorised access".
He said it will also look at 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".
Hughes said given that the investigation has already begun, "it would be inappropriate to comment further before the investigation is completed".
Prime Minister Jacinda Ardern said on Friday it would be "most useful now that we just allow the State Services Commission – rather than instead relying on he said she said - to produce their work".
Bennett said: "We shouldn't have to wait for the State Services Commission."
Bridges said last week Treasury's admission that no hacking occurred was an embarrassment and he mocked the agency for referring the "hacking" to police when only the search function was to blame.
Even the Finance Minister said last week that Treasury should have sought out more information before going to the police. He said he was "very disappointed that the Treasury did not seek to find more information".
Robertson has defended himself saying he was relying on the advice of Treasury, which the Prime Minister echoed in her defence of the Finance Minister.
Bennett said it's time Robertson and Little "tell us now what they knew". She said it's time they "stopped covering this up and let us know exactly what happened".