The Prime Minister says the fate of two large industrial plants are very different cases

In Southland, mining company Rio Tinto is pulling the plug on the Tiwai Point aluminium smelter.

And in Northland, Marsden Point Oil Refinery is scaling back operations, and looking at changing to an import terminal rather than processing crude oil into fuels.

Prime Minister Jacinda Ardern says there's still value in keeping the refinery running.

She says we need to continue importing oil and there's ongoing interest and many factors involved.

Refining New Zealand has ruled out shutting the plant completely.