All Blacks head coach Steve Hansen and Ian Foster have been a successful partnership and are signed until after the Rugby World Cup 2019.

A senior New Zealand Rugby official says it would be "hard to say no" to a third World Cup term for Steve Hansen if the All Blacks win the 2019 title.

NZR's general manager of rugby Neil Sorensen said there was no guarantee Ian Foster would take over the top job after the Japan tournament.

In an interview with Newstalk ZB on Sunday, NZR's second in charge indicated the same succession plan invoked after Sir Graham Henry's retirement is not necessarily a given this time around.

DAVID ROGERS/GETTY IMAGES Asistant All Blacks coach Ian Foster lacks overseas experience, despite being second in command since 2011.

Hansen stepped up from assistant coach to take over Henry directly after the 2011 Rugby World Cup victory in New Zealand.

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However, Sorensen told Newstalk ZB on Sunday that Foster - the All Blacks' assistant coach since 2012- is no certainty for the job and Hansen could carry on after the 2019 Rugby World Cup in Japan.

"I can tell you that Fozzie is really clear, and we're clear at our place, that when he signed with us to extend his contract, he said 'I'm worried - maybe I need to go offshore for a while and come back'.

"He made that decision to stick around with a successful All Black side...when the panel sits down they will have to take that into account. Fozzie will be sitting there thinking 'maybe I should have gone offshore and it will count against me'

"He is not sitting there saying 'I'm next after Steve Hansen. He will be putting his hand up like everybody else.

"Anyone with a decent sporting brain knows maybe half a dozen or more guys out there are capable of stepping into that environment and doing a fantastic job. The 16 or 15 people around Steve Hansen are pretty good operators as well.

Foster's lack of overseas coaching experience could count against him.

Hansen had minimal head coaching experience in New Zealand when he was appointed head coach but he had successful terms when he coached Wales.

"We're not complacent...one of the challenges might be we win the World Cup and Steve Hansen says 'I want to have another crack, I'm only 58. It would be bloody hard [to say no to Hansen] after three victories," Sorensen told Newstalk.

Sorensen said the process would be transparent and had already been signed off by the board.

He also confirmed that overseas-based Kiwis such as Ireland's success story Joe Schmidt would be eligible to step straight into the All Black job after the next World Cup.

"We will ensure that when we go to market in December 2019 that there are as many Kiwis as possible available. That's got to be our job. Our plan of attack is to make sure that those coaches overseas know what our process is and what we are looking for," he told Newstalk.

"I know there have been limitations in the past of people coming back, making sure they are familiar with our environment first.

"But we've loosened the requirement for the All Black coach to match Super coaches — all Kiwi coaches offshore will be available. We want them to be available to coach the All Blacks."

Of the coaches who do go overseas, Sorensen said they were always in the picture and never gone from the NZR family.

Schmidt is contracted with Ireland until the end of the 2019 tournament and Warren Gatland will also end his 12-year association with Wales then.