Education Minister Anne Tolley is instructing staff in her ministry to survey schools immediately to gauge national truancy rates and brief her on the fight against non-attendance.
Officials admit the latest national truancy figures up to 30,000 children each week are nearly three years old.
They could only guess how many children were absent on any given day, and had not delivered on reduced truancy targets, one said.
A biennial week-long survey of schools to collect crucial truancy figures, to have been held last year, was ditched while a new electronic attendance tracking system was implemented in some schools.
The last survey, in 2006, showed up to 30,000 children 4.1 per cent of the 750,000 primary and high school pupils were truant each week. It brought claims that the government was fighting a losing battle against a "truancy tidal wave".
A further "lost tribe" of 2500 long-term truants are not even enrolled. They are thought to represent a hardcore of young offenders before the youth justice system.
The electronic tracking system will provide more accurate data, but problems have delayed its implementation. Only about 250 of the 2700 schools are believed to use it. Just a handful of schools took part in a trial of the new system late last year and the data was of little use, officials say.
"If that information had come out, we would have known what the attendance and non-attendance picture was," a ministry official said. "So we share the disappointment. We feel it."
The ditched survey was "the only information we have nationally on attendance. We have nothing else".
Mrs Tolley said she was surprised and disappointed that Labour had not demanded last year's truancy survey, which would have provided up-to-date non-attendance figures.
"This means the last solid data we have is from 2006. That is unacceptable and I will be directing officials to undertake a survey as soon as possible so we can understand the true size of the truancy problem and work with schools and communities to ensure that more children are regularly engaged in school."
Getting more children back in class was a priority, especially when an estimated 150,000 pupils were failing.
Results from this year's survey would not be available till 2010.
Labour education spokesman Chris Carter said "snapshot" surveys did not provide accurate truancy information as figures were easily skewed by one-off events.
He had not been responsible as minister for ditching the survey. "At no point was I asked about it. I assume it was advice from officials."
The electronic system would eventually provide a much clearer picture. "We know there is a truancy problem. No one's disputing that. But telling us how many kids are away isn't solving the problem."
Ministry senior manager Tina Cornelius said the electronic tracking system, which is not compulsory, was likely to replace the biennial survey, depending on schools' uptake.
- The Dominion Post