Declining Eddie Jones's jovial offer of a gold jersey, Steve Hansen is back in black - and the Kiwi camp couldn't be happier.

New Zealanders were outraged when the World Cup-winning coach joined Jones's Wallabies prior to the tournament in France with Prime Minister Chris Hipkins joking they may have to cancel his citizenship.

All Blacks hooker Dane Coles sounded hurt, declaring he was "gob-smacked" when told Hansen had been helping out their arch rivals.

Jones said he and Hansen were great mates and he'd asked him to give a fresh perspective on the Wallabies, who were winless through five games in 2023 before their opening pool game victory over Georgia.

But 64-year-old Hansen, who steered New Zealand to glory in the 2015 tournament, has shared the love around, joining the All Blacks at their Lyon base.

New Zealand scrum coach Jason Ryan said Hansen was running his eye over the set-up following their bitter loss to France in Paris in their first taste of the World Cup.

"He's here until Wednesday and it's been good," Ryan said.

"He's arguably the greatest coach we've ever had so it's really special to have him in here, really special."

Both with ties to Canterbury rugby in New Zealand, Ryan said that Hansen had long been a big influence on him.

"On a personal level he's been unbelievable for me right through my Super Rugby career and right into the All Blacks," he said.

"He's someone I stay in contact with all the time and to have him in here, he's got a beautiful eye on him and drops a few good one-liners in.

"But he also helps the coaches and wants the All Blacks to be better first and foremost."