Former New Zealand rugby union player Jonah Lomu (C) and members of the Ngati Ranana London Maori Club take part in a haka during a photocall in central London on September 16, 2015. The 2015 Rugby Union World Cup begins at London's Twickenham Stadium on September 18, 2015. AFP PHOTO / LEON NEAL (Photo credit should read LEON NEAL/AFP/Getty Images)

Jonah Lomu died from cardiac arrest related to his kidney condition, family spokesperson John Hart, the former All Blacks coach, said.

At a press conference to announce funeral and ceremonial arrangements for the rugby legend, who died overnight on Tuesday, Hart revealed that Lomu's wife Nadene was struggling to come to grips with the sudden loss of her husband just a day after arriving back from Dubai following the Rugby World Cup in England

He said Lomu had been in good health and had "a magic time" at the World Cup.

The 40-year-old rugby star had gone to bed on Tuesday night just fine but he was found dead in the morning.