John Key says it's time for Kiwis to return the favour to Jonah Lomu - who gave so much to others when he was alive.

The Rugby Players Association has set up a trust to look after his sons after revelations the All Black great was broke at the time of his death.

The Prime Minister told Leighton Smith even if Jonah Lomu did mis-manage his money, he wouldn't be the first athlete to do so, in fact there's a long list of them.

John Key is suggesting a commemoration game at Mt Eden might be one way to pay Jonah Lomu back for his charitable generosity.

"He looked to me like a guy that gave enormously, gave too much in terms of his time and resources, but that is what it is. That was Jonah, and maybe it's time for us to give back."