Prince Philip, the husband of Queen Elizabeth II, has died at the age of 99.
The Royal Family Twitter account confirmed the news on Friday night.
"It is with deep sorrow that Her Majesty The Queen has announced the death of her beloved husband, His Royal Highness The Prince Philip, Duke of Edinburgh," it said.
"His Royal Highness passed away peacefully this morning at Windsor Castle."
The Royal Family website has been made unavailable while "appropriate changes" are made.
Newshub will air a special at 8am on Saturday morning on Three regarding Prince Philip's death.
New Zealand Prime Minister Jacinda Ardern has expressed New Zealand's sorrow at the Duke of Edinburgh's death.
"Our thoughts are with Her Majesty The Queen at this profoundly sad time. On behalf of the New Zealand people and the Government, I would like to express my sincere condolences to Her Majesty and to all the Royal Family," Ardern said.
"Prince Philip will be fondly remembered for the encouragement he gave to so many young New Zealanders through The Duke of Edinburgh’s Hillary Award. In over fifty years of The Award in New Zealand, thousands of young people have completed life-changing challenges through the programme.
"New Zealanders will also remember The Duke of Edinburgh’s enormous support for Her Majesty The Queen. His time as royal consort exceeded that of any other royal consort in British history. His Royal Highness accompanied The Queen on her ten visits to New Zealand, the first being in 1953, and the last in 2002."
The Prime Minister said that she had directed that flags on all Government buildings and naval vessels be flown at half-mast.
The Government is awaiting details from the Palace concerning the arrangements for The Duke of Edinburgh’s funeral. Following the funeral, a national memorial service will be held in Wellington. More details will follow once arrangements have been confirmed.
British Prime Minister Boris Johnson says the nation's thoughts are with Queen Elizabeth.
"We remember the Duke ... above all for his steadfast support for Her Majesty the Queen, not just as her consort, by her side, every day of her reign, but as her husband, has strength and stay of more than 70 years. And it is to Her Majesty, and her family, that our nation's thoughts must turn today.
"We give thanks, as a nation and a kingdom, to the extraordinary life and work of Prince Philip, Duke of Edinburgh."
The Duke of Edinburgh had experienced a number of health scares in recent years. He received a coronary angioplasty in 2011 and had two hospital stays in 2012 while receiving treatment for a bladder infection.
He was also treated for various ailments in 2013 and 2017, and had hip surgery in 2018.
Most recently, he was hospitalised in February 2021 for what Buckingham Palace said was a "precautionary measure" after he felt ill. A royal source said he did not have a COVID-19-related illness.
Earlier, in 2019, the prince escaped unhurt when his Land Rover flipped after colliding with another car.
Prince Philip and the Queen celebrated their 73rd wedding anniversary in November. Their relationship has been dramatised in the Netflix show The Crown.
He was the longest-serving consort in British history.
More recently, the prince was rarely seen in public. He stepped down from official engagements in August 2017 after completing more than 22,000 solo events and thousands more alongside the Queen.
During his lifetime Prince Philip visited New Zealand 15 times. In 1953 he was at the side of the newly crowned Queen as the couple visited 46 towns and attended 110 functions. The towering prince was often out of frame as the camera focused on his wife.
His support for her was steadfast, even in difficult moments like when a protestor threw a T-shirt at her during the 150th anniversary of the signing of the Treaty of Waitangi in 1990.
Prince Philip also travelled to New Zealand without the Queen five times. In 1956 he even made it to the Chatham Islands - the only royal ever to do so.
In 1992 he was here in his role as president of the World Wildlife Fund, and in 1997 he attended a six-day Duke of Edinburgh Awards forum in Wellington, where he handed out almost 300 gold awards to young recipients.
The Duke was also a keen conservationist, and in 1995 he arrived in New Zealand two days before his wife and took the opportunity to visit the stitchbird sanctuary on Mokoia Island in Lake Rotorua.
Given a traditional welcome, the Prince also lined up for the hongi. But the procession of people wanting to rub the royal's nose grew and grew, prompting the Duke at one stage to ask, "How many more?" At 36 he called it a day.
Prince Philip again showed his independent streak when he waded into the political issue of scientific monitoring of French nuclear testing in the Pacific. New Zealand wanted it - the United Kingdom wouldn't comment, but the Prince did.
"If there is a suspicion that it is doing damage," he said. "Then I think naturally if you're concerned with the conservation of nature you ought to make sure whether it is or it isn't."
The Prince's most recent visit to New Zealand was in 2002. On that trip, he once again took the time to give out the Duke of Edinburgh Award to young people who had completed the programme he established in 1956.
It wasn't the end of his connection to this country. In 2012 Prince Philip was made an additional member of the New Zealand Order of Merit - an honour bestowed by, who else, his wife the Queen.