Dame Tariana Turia is slamming the Ministry of Health, following allegations it misled the Prime Minister about the scale of the 2012 youth suicide crisis.
That year 144 youths took their own lives, 19 of whom were from Northland.
NZME reports that officials did not detail the number of cases, or their severity, to then Prime Minister John Key, in an effort to keep the crisis out of the headlines.
Dame Turia, who was Associate Health Minister at the time, told Newshub she believes the Ministry has been caught napping.
"I think that that's butt covering behaviour and not acceptable at all.
"We need to own up when things are not going right and we need to own up about what can be done."
Dame Tuira says after the spike of suicides in 2012, resources were brought in to support families and other students at Kamo High, where two suicides within a month prompted some copycat attempts.
"But the problem is we sent people in to work with these families and then we go back to being dismissive about the issue so the numbers climb again, as they have."
Even though mental health programmes are proven to reduce suicides, Dame Tuira says they struggle due to insufficient funding.
"We worry about the cost, because there's only x-amount of dollars in the health budget, but we shouldn't be counting the cost in people's lives that have been lost.
"It's horrendous… in government we rely on the advice of officials, and if officials are not bold and brave enough then we don't get the right response.
"And we were quite unaware of the huge numbers who were dying up there in the north."
New Zealand's teen suicide rate is the worst in the developed world.
The Ministry of Health rejects any allegations that they didn't inform then Prime Minister John Key of what was happening in Northland.
A spokesperson told Newshub "there was no intention not to inform the Prime Minister of the time. Nor should there be any suggestion we were inappropriately withholding information from anyone else. A number of Ministers were regularly receiving information at the time."