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."