Finance Minister Grant Robertson says he "expects better" of the Treasury after the department admitted to accidentally posting parts of the Government's financial statements on its website days ahead of their official release.
It's the second major data gaffe from the Treasury in months, after fragments of the May Budget also ended up online early.
Secretary to the Treasury Caralee McLiesh - who only started in the role weeks ago - says last Thursday a section of the 2019 Financial Statements – officially released on Tuesday this week – were posted on its site for about an hour due to "human error".
"The error was discovered by the Treasury and the content removed. It was not accessed by anyone internally or externally," she said in a statement.
McLiesh said she had apologised to Minister Finance Grant Robertson over the blunder.
"While the information was not accessed and the error was fixed quickly, the fact that it was on our website is unacceptable," she said.
"It was human error that led to content being pasted into the wrong place. Those involved took quick action to fix the error as soon as they discovered it. We have implemented process changes to prevent this happening again."
In a statement, Robertson described the situation as "very disappointing".
"I expect better," he said.
"It emphasises the importance of the Murray Jack review and the Treasury implementing the recommendations from that."
But the Opposition says the error reflects a lack of leadership and comes on top of other data breaches, including by the Ministry of Arts Culture and Heritage.
"Ministers aren't directing their departments and the Prime Minister isn't holding her ministers to account," National Party leader Simon Bridges said.
"A second breach of this kind under Grant Robertson is unacceptable."
The Government's books this week revealed it had posted a $7.5 billion surplus.
The Treasury caused a political storm ahead of May's Budget after the parts of the tightly guarded documents were accidentally put on its website early, a flaw made public by the National Party.
The blunder led to calls for the resignation of both Robertson and McLiesh's predecessor Gabriel Makhlouf.
Makhlouf – who ended his scheduled tenure and is now the head of Ireland's central bank – caused a stoush over the situation by initially saying the department had been "hacked".