New Zealand will distribute free sanitary products in schools to combat "period poverty" among the disadvantaged, Prime Minister Jacinda Ardern said Thursday.

Ardern said research showed about one in 12 young people skipped school because they did not have access to period products.

"Young people should not miss out on their education because of something that is a normal part of life for half the population," Ardern said.

"Providing free period products at school is one way the government can directly address poverty, help increase school attendance, and make a positive impact on children's wellbeing."

She said the programme, which begins in June and will cost NZ$25 million (US$18 million) over three years, followed a successful pilot scheme that started last year.

Ardern said participants in the pilot showed increased engagement at school and improved educational outcomes.

Period poverty occurs when women and girls lack the money for tampons, pads or menstrual cups, or medication for cramps.

Globally, campaigners say the issue has a direct effect on girls' education, with a knock-on impact on work opportunities, thus deepening gender inequality.

Scotland last year became the first country in the world to provide universal access to free period products.