The Minister for Women wants to know why the pay gap between men and women is the biggest it has been in six years.
Statistics New Zealand's quarterly income survey shows wages are increasing, but at a much faster rate for men.
The median weekly wage for everyone is up $26 from a year ago to $621 before tax.
But for men, the average hourly earnings rose 4.6 percent to $24.07, while for women it rose only 2.4 per cent to $21.23.
The gender pay gap has grown to 11.8 percent, up almost two percent from a year ago.
Minister for Women Louise Upston said she wanted to find out why.
"Any gender pay gap's unacceptable. I have asked the Ministry to do some further analysis to find out what's behind it," she said.
A spokesperson for the lobby group Pay and Employment Equity Coalition, Angela McLeod, said many women were being undervalued.
"Caregiving, school support work - all those caring roles that women tend to be in aren't being valued," she said.
"That's the really sad thing, that it comes from an unconscious bias."
Green Party spokesperson for social development Jan Logie said the stats made for depressing reading.
"It makes a real difference in terms of women's ability to feed and clothe and house themselves," she said.
"It's a major issue - an almost 12 percent gap affects people's retirement and their everyday life."
She said the Government was ignoring the problem.
"It comes down to there being no plan in place to reduce the gap," she said.
"When the Government came to power, one of the first things they did was disestablish a unit - the Pay and Employment Equity Unit - that was supposed to be focused on reducing the gap."
Ms Upston said she could not explain why the gap was growing, but defended the government's approach to pay equity.
"One of the challenges can be for women who take time in and out of the workforce to raise families," she said.
"What we're really encouraging employers to do is take up legislation that gives women flexibility in the workplace.
In June, the Human Rights Commission recommended the government set a 2020 target for evening out pay rates.
Business New Zealand's chief executive Phil O'Reilly said that was unlikely, but admitted companies needed to do more.
"You'd hope by then we're really starting to narrow the gap because some of it exists in the current workplace," he said.
"The sad thing is we've been talking about this for a long time without much success so I think it's a case of redoubling efforts.
"We've got to get everyone to own the issue - this is not a women's issue, it's a Government and business issue and everyone needs to be accountable."
The survey also showed average wages for European workers were still higher than those for Pacific and Asian people, but that gap was closing.
Of the regions, Southland workers had the highest average weekly wage of $693, while Manawatu-Whanganui had the lowest of $510.
Statistics New Zealand surveyed 30,000 people.