The oil supplier Refining New Zealand is winding down its search for oil from a spill at Marsden Point.
It said no traces were found during this morning's sweep of Whangarei Harbour, after oil began leaking from tanks on a vessel unloading crude yesterday afternoon.
Refining New Zealand said it protected the harbour's rocks and beach with booms and deployed a skimmer to remove oil from the surface.
Refining New Zealand said the operation was being scaled back although teams remained on the lookout for any more oil.