All Black legend Jonah Lomu was confirmed as one of several rugby and league players who will be involved in a charity boxing event in Auckland on December 3.

The 36-year-old challenged the most recent player to be compared to him, Sonny Bill Williams, to a fight, but the All Black centre's management declined the offer.

"I respect Sonny Bill Williams, but I'd happily step into the ring with him,'' Lomu told APNZ.

Lomu,  the recipient of a kidney transplant, revealed that he had not fear about the risks of stepping into the ring and had informed Grant Kereama, who had donated the kidney, who was supportive of the decision.

"There's no difference between this and playing rugby. Life is too short to be wrapped up in cotton wool,'' he said.

"I can't wait to get it on.''

Also on the bill for the charity fight are retired All Blacks Christian Cullen, Troy Flavell and Carlos Spencer, while current star Liam Messam will also be fighting.

There are also a number of former league stars including Wendall Sailor, who represented Australia in both rugby codes.

The event will raise money for the Prostate Cancer Foundation of New Zealand, with the line-ups to be announced on November 1.

Each bout would consist of three two-minute rounds.