Ms Ardern - described by Vogue this year as "the anti-Trump" - told reporters at the United Nations General Assembly in New York her country has no plan to sign the US president's "Global Call to Action on the World Drug Problem" document.

The paper seeks a commitment towards a crackdown on the supply and smuggling of drugs and has a focus on synthetic substances.

Ms Ardern, the leader of New Zealand's centre-left Labour Party, told reporters her country had distinct challenges around the types of drugs that were causing issues - but also wanted to take a "health approach" with its domestic policy.

"We want to do what works, so we are using a strong evidence base to do that," she said.

"It's not our intention to [sign up] and there are a number of other countries who haven't either."

The US says 124 countries have already agreed to the document, which is being promoted at an event this week by US President Donald Trump with hopes of getting more on board.

In the lead-up to the General Assembly, the US ambassador to the United Nations, Nikki Haley, said the president would be making clear the US would "be generous to those that share our values".

Meanwhile, Ms Ardern, who has become a rockstar of the global left since her meteoric rise to power last year, will be using her megaphone in New York this week to make a case for global cooperation on issues such as climate change, human rights and poverty.

The 38-year-old is also making a series of high-profile television appearances and is travelling with daughter Neve in tow, having become only the second world leader to have a child in office in June.

She said her direct interactions with Mr Trump over the week - during a reception and leaders' event - would likely be minimal.

Australian Associated Press