Police are refusing to release new domestic violence statistics because the results are horrific and would embarrass the Government in election year, Women's Refuge and the Green Party say.
Police have adopted a new measuring tool, the Ontario Domestic Assault Risk Assessment (Odara), which predicts how likely domestic violence offenders are to reoffend.
At a semi-confidential sector briefing last October, police shared initial figures. They showed New Zealand scores on the Odara index were much higher than those recorded in Canada, where the system originated.
However, efforts by Women's Refuge and the Greens to get further information from the police, including Official Information Act requests, have been rebuffed.
Police told them statistics were still being "evaluated", but neither group accepts that reason.
The police decision comes after Fairfax Media reported last month that a specially commissioned report by a domestic violence task force had yet to be released. This was in spite of it being completed five months ago.
Panel members were dismayed and suggestions had arisen that the report had been "buried".
The Odara scale assigns scores of one to 13 to the likelihood of domestic violence offenders reoffending. Scores of seven and above are considered very serious.
In early statistics, 42 per cent of New Zealand offenders were rated seven and above, against 7 per cent in Canada.
Police conducted a test run of Odara against historic incidents to measure its accuracy and then conducted live use on major domestic violence incidents since at least late 2012. But they will not hand over any of that data.
"We're not being mischievous," Women's Refuge spokeswoman Kiri Hannifin said.
"We just want to know the common areas where men score highly on, so we can work with women to keep them safe and put our resources into that area.
"It's disappointing that it's been seven months [since the briefing] when domestic violence is such a significant problem in New Zealand."
Even draft data would help, Hannifin said.
"We can't afford to do research ourselves, we run on the smell of an oily rag so, when another agency does research, we rely on them sharing it with us.
"I am sure they are worried about the media [reaction to the figures], but it is a big issue which costs millions of dollars a year. We don't think we are asking for too much."
Green Party spokeswoman on women, Jan Logie, who had two OIA requests declined, said: "It looks as if the Government are holding on to the report because it is showing levels of domestic violence that are much more serious here than in comparable countries - and the Government are failing to do anything about it.
"The police are saying the data is still being questioned - and I question that.
"The Government have made a big deal this year that domestic violence is a big priority for them and they responded by keeping the task-force report quiet, as well as this data secret and out of the public domain, and slashing funding from core services."
Jane Drumm, chief executive of the charity, Shine, said she didn't share Women's Refuge and Logie's concerns, but described the initial data she saw as "very scary".
Police national operations manager Superintendent Barry Taylor said the October meeting used provisional data which "was not suitable for wider release".
Taylor hoped the evaluation and data would be "available later this year".