Conservative Party leader Colin Craig's comment that New Zealand women are the most promiscuous in the world and don't deserve state-funded contraception is being described by cabinet ministers as stupid and offensive.

The government plans to spend $1 million to pay for doctor visits and long-acting reversible contraception for beneficiaries aged 16-18 from July as part of this month's budget.

Mr Craig says it's an extension of welfare that discourages beneficiaries taking personal responsibility.

"We are the country with the most promiscuous young women in the world. This does nothing to help us at all," he told Radio New Zealand.

Social Development Minister Paula Bennett, who is in charge of the contraception policy, says she doesn't agree.

"I actually find it offensive to New Zealand women, it's the sort of old fashioned view I don't think has any merit in modern society," she told reporters.

Justice Minister Judith Collins said: "I think it's a stupid statement."

She didn't have an opinion on Mr Craig, saying she didn't know him and had never met him.

Prime Minister John Key says he doesn't believe there's any evidence to support Mr Craig's comment.

"This is a logical thing to do, which is to provide support for young, vulnerable women and to give them a voluntary option," he said.

Asked whether he could work with Mr Craig if the Conservative Party won seats in parliament at the next election, he said National formed partnerships with parties even though it didn't agree with some of their views.

"It doesn't mean we can't work constructively."

A spokesperson said Mr Craig was using data from surveys by condom manufacturer Durex and Marie Claire magazine, where New Zealand women reported having an average of 20.4 sexual partners - nearly triple the global average of 7.3.