Jacinda Ardern grimaces as she announces her resignation at a press conference in Napier, New Zealand, on Thursday. AP

The 42-year-old — who steered the country through natural disasters, the Covid pandemic, and its worst-ever terror attack — said she no longer had "enough in the tank".

"I am human. We give as much as we can for as long as we can and then it's time. And for me, it's time," she said at a meeting of members of her Labour Party.

READ MORE

Qantas flight lands safely in Sydney after mid-air mayday

Ukraine interior minister among 18 killed in helicopter crash

Ardern said she would step down no later than February 7, less than three years after winning a landslide election to secure her second term in office.

Since that 2020 peak of "Jacindamania", Ardern's government has struggled -- its popularity hampered by soaring inflation, a looming recession and a resurgent conservative opposition.

Jacinda Ardern grimaces as she announces her resignation at a press conference in Napier, New Zealand. AP

"I believe that leading a country is the most privileged job anyone could ever have, but also one of the more challenging," Ardern said.

"You cannot and should not do it unless you have a full tank, plus a bit in reserve for those unexpected challenges."

Ardern won international acclaim for her empathetic handling of the 2019 Christchurch mosque massacre, in which 51 Muslim worshippers were killed and another 40 wounded.

Later that year she was praised for her decisive leadership during the fatal White Island (also known as Whakaari) volcano eruption.

On Thursday she cited her government's actions on housing affordability, climate change and child poverty as further sources of pride.

"And we've done that while responding to some of the biggest threats to the health and economic wellbeing of our nation arguably since World War II," Ardern said.

Jacinda Ardern and partner Clarke Gayford pose with their baby daughter Neve Te Aroha Ardern Gayford. File/AFP

Featured on the covers of British Vogue and Time magazine, there was a perception that Ardern was more popular abroad than she was at home.

At her peak she was a domestic force, but her government has been steadily sliding in the polls over the last year.

"It's about time. She's wrecked the economy and food prices have skyrocketed," said Esther Hedges from Cambridge on New Zealand's north island.

"I'm not happy with her and I don't know anyone who is," the 65-year-old added.

Christina Sayer, 38, said Ardern was "the best prime minister we have had".

"I like the type of person she is and she cares about people. I'm sorry to see her go."

The stress of the job has been evident, with Ardern showing a rare lapse of poise last month when she was unwittingly caught calling an opposition politician an "arrogant prick".

New Zealand actor and Hollywood veteran Sam Neill said Ardern was frequently targeted by social media "bullies".

"She deserved so much better," he said in an online statement.

Agence France-Presse