Tributes have started flowing from the world over after New Zealand's Māori King, Kiingi Tuheitia died aged 69, just days after the celebration of his 18th year on the throne.

The death was confirmed by the Kiingitanga's social media early on Friday morning.

"Kiingi Tuheitia Pootatau Te Wherowhero VII has died peacefully this afternoon, accompanied by his wife Makau Ariki and their children Whatumoana, Korotangi and Ngawai Hono I Te Po," it read, in te reo, the Māori language.

According to media reports, Kiingi Tuheitia was in hospital recovering from heart surgery.

"It didn't quite go as we had all hoped," the Kiingitanga's chief of staff Ngira Simmonds told Radio NZ.

"In the early hours of this morning, he passed away peacefully."

The Māori king position was founded in 1858, aiming to be a unifying movement for all Māori tribes.

It is a largely ceremonial but hugely consequential role in New Zealand.

In recent months, Kiingi Tuheitia has co-ordinated national unity talks for Māori in response to the centre-right government's policies.

"He believed in the vision of his ancestors. He understood his role and his duties," Mr Simmonds said.

"He wanted to serve and do everything that he could and exhaust every effort to bring unity to our people and indeed the nation at large.

"He served until the very last."

Leaders pay tributes 

King Charles and leaders across New Zealand and the Pacific have paid tribute to Kiingi Tuheitia.

King Charles said he and Queen Camilla were "profoundly saddened".

"I had the greatest pleasure of knowing Kiingi Tuheitia for decades," he said in a message of condolence.

"He was deeply committed to forging a strong future for Māori and Aotearoa New Zealand founded upon culture, traditions and healing, which he carried out with wisdom and compassion.

He recalled with "immense fondness" meeting Kiingi Tuheitia many times including at the Tuurangawaewae Marae in 2015 and at Buckingham Palace last year.

"His death is a particular shock in view of the fact that I had only very recently spoken to Kiingi on the telephone at the beginning of August," he said.

Former New Zealand prime minister Dame Jacinda Ardern described Kiingi Tuheitia as "an advocate for Māori, for fairness, justice and prosperity".

"You worked tirelessly on building understanding and knowledge of our shared history and in doing so, strengthening Aotearoa."

"I'm sure that the people of Tonga feel the loss of this great leader of the Pacific," said Hu'akavameiliku Sioasi Sovaleni, Tonga's prime minister.

"Our thoughts and prayers are with New Zealand."

The seat of the Māori king is held by the Tainui tribes in the Waikato and it is not yet clear who will take the throne.

It is expected that Kiingi Tuheitia will lie in state at Tūrangawaewae Marae for five days before he is taken to his final resting place on Taupiri Mountain.

The next few days would be for local tribes to mourn.

Others would then be welcomed to the marae, including international dignitaries, followed by a Māori funeral, known as a tangihanga.

Source:ABC