Prime Minister Jacinda Ardern learned of the Queen's death when a police officer shone a light into her room at 4.50am today.

"Just a night prior I'd been reading about the news about the state of her health...so when the torchlight came into my room, I knew what it meant," Ardern told media this morning.

She said it was with "great sadness" that New Zealand has woken up with the news of the Queen's death.

"Here is a woman who gave her life utterly to serve others."

The Prime Minister said she remembered asking the Queen what it was like to raise children in her role.

"She was someone who offered up her opinion very freely but who was also very stoic because she never really had those choices, she had to serve and be a mother and be a grandmother so I learned much for observing her.

"She pondered for a moment and essentially said you just have to get on."

One of Ardern's fondest memories was a conversation she had with the Queen during lockdown in 2020.

She recalled asking the Queen how she was passing the time and she responded saying she had been listening to the radio about a political prisoner.

The Queen reportedly said listening to that made "one feel rather small".

"It was a very human conversation".

Ardern noted how the role of a leader could make you distant from people but she never got the sense that had happened to the Queen.

"She was extraordinary."

Ardern also recalled gifting the Queen a Polaroid image taken during a visit to New Zealand more than 50 years prior.

"She recalled where it was taken and even what had made her laugh at the moment the photo was taken," Ardern said.

"I know that I speak for people across New Zealand in offering our deepest sympathy to members of the Royal Family at the passing of the Queen," Ardern said in an early morning statement today.

"To us she was a much admired and respected monarch, to them she was a mother and grandmother."

Ardern said the Queen was a much-loved and admired monarch, whose record reign of 70 years is a testament to her and her commitment to us all, Ardern said.

Ardern acknowledged how widely felt this news would be to people around the world, describing the Queen as a constant figure who had been a part of people's lives for generations.

"People throughout the world will be feeling an acute sense of loss at this time and New Zealanders most certainly share that grief.

"The Queen was a much respected constant through unprecedented global change."

Ardern said the Queen had visited New Zealand on 10 occasions throughout the years - with a notable first tour in the summer of 1953-1954 when she and the Duke of Edinburgh visited 46 centres and attended 110 functions.

Queen Elizabeth II and Prime Minister Jacinda Ardern pictured in 2018. Photo / Getty Images

The monarch was in New Zealand for the 1974 Commonwealth Games in Christchurch and again in 1990 when the Commonwealth Games were held in Auckland.

She had also mourned with New Zealand, Ardern said, when tragedies struck close to home - namely the Tangiwai rail disaster and the Christchurch earthquake in February 2011.

"I know a number of New Zealanders who had the privilege of meeting Her Majesty were struck by her keen interest, warmth and sense of humour.

"I remember in my very first meeting with Her Majesty being humbled by her intimate knowledge of New Zealand and its triumphs and challenges."

Plans for a state memorial service are now under way, the Prime Minister confirmed, with local events around the country also expected.

A representative of New Zealand will attend the Queen's funeral service also, she said.

Flags around the country will fly at half-mast as a mark of respect for the Queen's death.

Ardern also confirmed that the new King Charles now becomes New Zealand's new Head of State.