New Zealand's government is prepared to force private businesses to appoint more women directors if companies don't make sufficient progress themselves, Minister for Women Julie Anne Genter says.

The government said last week that it will ensure half of all directors on state sector boards and committees are women by 2021, compared with 46 per cent at the end of 2017.

By comparison, women held just 19 per cent of directorships across the 159 companies listed on the main board of the New Zealand stock exchange, according to a report in January.

"We're awaiting the next report, and I'm keen to see where they get to," Genter told Television New Zealand's Q+A program Sunday.

"If they're not going to make progress, if it's going to sit there at 19 per cent, then we might have to start thinking about ways government can incentivise them."

New Zealand Prime Minister Jacinda Ardern. AAP

Under Prime Minister Jacinda Ardern, the world's youngest female leader, the government is forging ahead with plans to change the way women are treated in society and allow them to achieve their full potential, including an ambitious goal to eliminate the gender pay gap.

Genter said a range of tools are potentially available to the government to "incentivise" private businesses to change, including imposing quotas.

"The evidence is mixed on how successful that is," she said. "Quotas in some places have been successful, but they also can have perverse consequences. So what I would say is let's start by putting up the challenge."

In Australia voluntary targets rather than quotas have been in place, but there's been some push-back against them.

The chairman of the 30% Club Australia, the lobby group pushing for 30 per cent female representation on the boards of the nation's largest 200 companies, Nicola Wakefield Evans, says parity should be the ultimate goal in business but has stopped short of calling for quotas.

Women currently make up 27.7 per cent of board positions, according to the Australian Institute of Company Directors, which works with the 30% Club to achieve greater gender diversity on boards.

But Ms Wakefield Evans, who sits on several company boards, including as the non-executive director of Macquarie Group, has said that even when the ASX200 hits 30 per cent the gender diversity conversation should not stop.

The next target for these companies should be 40 per cent by 2022, she said, adding that this was her aspiration and was yet to go the 30% Club's corporate members for a formal decision.

-Bloomberg with BusinessDay