All Blacks legend Jonah Lomu has died at the age of 40.
Nadene Lomu, the wife and manager of the rugby great, said in a statement: "It is with great sadness that I must announce my dear husband Jonah Lomu died (overnight).
"This is a devastating loss for our family and may I ask that our privacy, especially the privacy of our two very young boys, be respected as we take them through this traumatic time."
A family spokesman told TV3: "I can confirm that Jonah Lomu died this morning ... it was totally unexpected.
"Jonah and his family arrived back from the UK last night."
Lomu had dealt with the severe kidney ailment nephrotic syndrome since 1995 which forced his premature retirement from international rugby in 2002.
After having a kidney transplant in 2004 he tried unsuccessfully to resume his professional career in Wales and France.
While his health seemed to improve he could not regain his former dominance and eventually retired from all rugby in 2006.
Since Lomu's transplant failed in 2011, he became reliant on dialysis.
He won 63 caps for the All Blacks during an impressive career which saw him regarded as rugby union's first global superstar.
A tweet from New Zealand Rugby chief Steve Tew read: "We're all shocked and deeply saddened at the sudden death of Jonah Lomu."
He added: "We're lost for words and our heartfelt sympathies go out to Jonah's family.
"Jonah was a legend of our game and loved by his many fans both here and around the world."
New Zealand's prime minister said the nation would be "devastated" by the loss of Lomu.
"He'll be remembered not only for being a truly amazing global sportsman and for his time on the field, and of course some of those incredible encounters that we saw in the '95 Rugby World Cup against England, he'll be remembered for his sportsmanship," John Key said.
"Someone that stayed on the field and shook the hands of the players when we lost the '95 Rugby World Cup (final to South Africa), and also in '99 and the France semi-final when we lost that game.
"But I'll also remember him for the work that he was doing for his charities."