New Zealand great Jonah Lomu has died suddenly at the age of 40.

The 63-time All Black and former winger's death was confirmed on Wednesday.

New Zealand Rugby chief executive Steve Tew said he was shocked in a statement via the All Blacks' Twitter account.

"We're all shocked and deeply saddened at the sudden death of Jonah Lomu," he said.

"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."

Lomu was diagnosed with a serious kidney disorder in 1996, but details about his death are unclear.