'Cancel his citizenship': New Zealand's PM weighs in on Steve Hansen

From the All Blacks to the prime minister, New Zealanders have been shocked by Rugby World Cup-winning coach Sir Steve Hansen's defection to help the Wallabies.

However, Hansen has downplayed his role against the Kiwis' arch-rivals, saying he's just helping out his mate Eddie Jones and will be gone by the end of the week.

All Black Dane Coles spoke for a nation when he was informed of Hansen's short-term role with the Wallabies.

"Shag what are you up to?," the surprised hooker said, referring to Hansen's nickname, when he was told of the defection.

"It hurts a little bit, to be fair. I'm actually gob-smacked ... he's a bit of an icon in the All Blacks setup.

"I'm actually a bit speechless. A bit disappointing but we can't do much about that."

Coles was the starting hooker for the All Blacks in the 2015 World Cup under Hansen, a tournament in which they beat Australia in the final for their third, and most-recent, title.

The shockwave of Hansen's move was clearly resonating back in Wellington, where Prime Minister Chris Hipkins was similarly aghast.

Asked by AAP what Hansen's punishment should be, Hipkins exclaimed, "We should cancel his citizenship", before laughing and quickly adding, "That's a joke just to be very clear".

Hansen jumped on the phone to Kiwi radio station Newstalk ZB to set the record straight.

"I'd just like to put everybody's mind at rest that I haven't joined the Wallabies for the Rugby World Cup," he said.

"I'm here for about three or four days at the request of Eddie, a good mate of mine, just to give him some feedback on what he's doing.

"Rugby is bigger than all of us, so (I'm) happy to do that."

Hansen said he was not being paid for his appearance in Paris this week as the Wallabies prepare for their final World Cup tune-up against France this weekend.

Australia are yet to win a match under Jones in his second term as coach, but Hansen said he liked what he had seen in his short time around the Wallabies camp.

"Australia are looking good actually," he said.

"They're just a young side that are coming together and they've got a coach that wants them to work hard and be better. I think they're buying into that."

France and Ireland are the favourites to win the tournament but Hansen raised doubts over both frontrunners.

He queried Ireland's ability to run deep given they have never been past the quarter-finals of a World Cup, and said France would find it hard to replace freshly injured five-eighth Romain Ntamack.

The 64-year-old saved his most effusive praise for the All Blacks, who face South Africa this weekend off the back of an unbeaten 2023.

"They're going great. They're exactly where they want to be," Hansen said.

"They know how they want to play (and) they're confident in each other."