There's disagreement within the National Party over Auckland's port.

Sir John Key has joined forces with fellow former Prime Minister Helen Clark in supporting relocating the port from prime waterfront land.

But his former senior minister, Steve Joyce, believes the port should stay.

Joyce told Kerre McIvor moving operations to Whangarei or Tauranga would require a huge infrastructure upgrade.

"The idea that you'd be able to do that without massive expense and dislocation of the existing communities, I think there's no way in the existing transport corridors that it wouldn't make things a lot worse."

He says shifting to Northland isn't exactly like hopping over the fence.

"It's a very strange for a port city to have its port 160 kilometres away. They tend to shift a lot shorter distances. If you look at Sydney, they shifted out to Botany Bay, but it's literally only 12km's still from the middle of Sydney."

Sir John told Mike Hosking this morning that it does not make sense to keep the port where it is. 

"It's very expensive to move it, but the problem with that argument is that it's also very expensive to maintain it. The differential between the two is not nearly as big a number, I think, as what people say."

 

• John Key, Helen Clark join forces to shift the port