Jacinda Ardern is in New York for the United Nations General Assembly this week, along with about 140 other world leaders.
US President Donald Trump is holding an event at the UN to promote the US document called the Global Call to Action on the World Drug Problem.
The document requires the countries which sign to develop national action plans to reduce the demand for illicit drugs, cut off supply at their borders and strengthen international cooperation.
Ms Ardern said New Zealand would not be among the countries signing the document.
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