A team of 40 people is working to clean up the remnants of an oil spill in Whangarei Harbour.
Hundreds of tonnes of sticky black fuel oil leaked into the harbour yesterday from the Hong-Kong-registered cargo ship Ning Po, which was berthed at Northport near Marsden Point.
An intensive clean-up operation cleared most of the oil from nearby beaches and the Marsden Cove marina.
Northland Regional Harbourmaster Jim Lyle said it appeared a systems failure on the cargo ship allowed fuel oil to escape through the ballast system.
He said some oil ended up on nearby beaches, but most of it was recovered from the water between the ship and the port.
"But the fact that the oil was captured between the ship and the port key structures was very lucky," he said.
"If all of that oil had actually spilled up into the harbour and ended up on to the beaches it would've been a very different operation, yeah, very nasty."
Mr Lyle said the bill for the clean-up would go to the owners of the Ning Po - who were flying out from Singapore to find out what went wrong.
In the meantime, Maritime New Zealand has detained the ship at Whangarei until it is been cleaned and repaired.