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A state funeral is to be held for Sir Edmund Hillary, who died this morning from a heart attack, aged 88.

In a statement, his widow, Lady Hillary, indicated the family thought such a funeral appropriate, "recognising the impact [Sir Edmund] has on all New Zealanders".

She added the family was comforted by messages of support from around the country and the world.

A date for the funeral would probably be fixed over the weekend as some family members were out of New Zealand and would take time to get home.

Among them is Sir Edmund's only son Peter, currently in Portugal.

The funeral will be broadcast on TVNZ.

Lady Hillary said Sir Edmund died peacefully in Auckland Hospital at 9am today after his heart gave out.

He had been in hospital since Monday but was due out and had been looking forward to coming home.

"He remained in good spirits until the end."

At the family's Remuera home this afternoon, step-daughter Susan Hayman also said Sir Edmund was in "high spirits" prior to his death.

The family wanted some time to themselves to come to terms with his passing, she said.

A spokesman for acting Prime Minister Michael Cullen said Prime Minister Helen Clark had been in contact with the family as Sir Edmund's health deteriorated.

"The offer was always to provide whatever assistance they wanted, on any sort of level," he said.

"I have just heard they have accepted the offer of a state funeral."

Documentary maker Tom Scott, a longtime friend, arrived at the Hillarys' home following the news.

Scott said he'd been working with Sir Edmund on a documentary about the mountaineer's work in Nepal and the resulting footage would be shown on the night of the funeral.

"We knew when we were making it (the documentary) that was the purpose of it and we were terribly sad," Mr Scott said.

"Everywhere we went there was this kind of cloud hanging over us because we knew we were making it to be played on the night he was buried - on the state funeral.

"But at the same time it was a tremendous honour and a privilege to be asked to make it.

"He's a great New Zealander.

"We will not see his like, the old cliche, for a long, long time.

"He was an extraordinary man."

Elsewhere, staff at Scott Base in Antartica lowered the New Zealand flag to half-mast as the mood quickly turned to one of great sadness.

Flags have also been lowered to half-mast at Parliament in Wellington.

A condolence book for Sir Edmund Hillary has been opened in Parliament, Speaker Margaret Wilson said.

Ms Wilson paid tribute to Sir Edmund, saying he was "a true New Zealand hero".

"Because of the significance of Sir Edmund to New Zealand, Parliament is offering New Zealanders the opportunity to express their condolences," she said.

"I have asked for a Book of Condolences to be opened. This is now available in Parliament House and I invite anyone wishing to pay their respect through messages of support and sympathy to come and sign the book."

Governor-General Anand Satyanand said the death of Sir Edmund Hillary was a great loss to his family and to all New Zealanders.

"Sir Edmund was a great New Zealander and his passing will be deeply mourned by people throughout the world. As Governor-General of New Zealand and on behalf of all New Zealanders, I extend my deepest condolences and those of my wife Susan, to Lady Hillary and Sir Edmund's family on their great loss."

Friend and climber Graeme Dingle described Sir Edmund as "a great human mirror of who we are, or who we like to think we are," calling the late icon "a national treasure".

Sir Edmund shot to international stardom as the first man to scale Mt Everest in 1953.

As the tributes began to flow in, Helen Clark described Sir Edmund as the best-known New Zealander to have ever lived and said his passing was a profound loss to New Zealand.

"Sir Ed described himself as an average New Zealander with modest abilities. In reality, he was a colossus," she said.

"He was an heroic figure who not only 'knocked off' Everest but lived a life of determination, humility, and generosity."

National Party leader John Key said Sir Edmund Hillary was a New Zealand hero.

"We will all feel the loss of a truly remarkable man whose achievements and humility have inspired New Zealanders for so long," he said.

Sir Edmund's last visit to Scott Base, which he was instrumental in establishing, was only last year.

"It was a very special time," said Antarctica New Zealand's senior representative at Scott Base, Dean Peterson. "He was a great gentleman who had a huge amount of tenacity not to mention a lot of willpower and boundless courage. This was in someone incredibly gentle and caring - an extremely rare combination of qualities."

Reserve Bank Governor Alan Bollard said Sir Edmund's special character was demonstrated in the fact that he was the only living New Zealander to have been chosen to feature on a New Zealand banknote - the $5 note.

In a sporting tribute, the New Zealand cricket team will wear black arm bands and observe a minute's silence along with the crowd before play starts on day one of the second test against Bangladesh at the Basin Reserve in Wellington tomorrow.

"Sir Edmund was a role model for all New Zealanders. His legendary story as both a humanitarian and adventurer has been, and will continue to be, inspirational to generations," Mr Key said.

"I offer the National Party's condolences to Sir Edmund's family and friends. I'm sure all New Zealanders will feel the loss of his passing."

He famously said of the ascent, carried out with with sherpa Tenzing Norgay: "We knocked the bastard off."

For a long time Sir Edmund refused to say who reached the summit first, but in his book View From The Summit he eventually made it clear.

"I continued cutting a line of steps upwards," he wrote.

"Next moment I had moved on to a flattish exposed area of snow with nothing but space in every direction. Tenzing quickly joined me and we looked round in wonder. To our immense satisfaction we realised we had reached the top of the world."

The conquest of Everest brought Hillary, then 35, lasting fame which was swiftly recognised when he was knighted on June 6, 1953.

Sir Edmund was typically modest about the award.

"I could see myself walking down Broadway, Papakura, in my tattered overalls and the seat out of my pants, and I thought 'That's gone forever. I'll have to buy a new pair of overalls now'."

In recent years Sir Edmund's health had been failing but he made a final visit in January 2007 to Antarctica, the scene of another of his triumphs.

He was made a knight of the Order of the British Empire in 1953 and, 42 years later, the Queen bestowed on him her highest honour - a knighthood in the Order of the Garter.