Cleaning up an oil spill in Tauranga Harbour will take another four to five days, the Bay of Plenty Regional Council says.
Oil from the spill has washed ashore covering about 300 metres of coastal vegetation at the southern end of the harbour, near Maungatapu Peninsula.
Mobil has taken responsibility for the spill, saying the fuel oil leak came from one of its pipelines while a ship was refuelling on Monday.
It said it would cover the financial cost to the council of the clean-up.
The council's deputy chief executive, Eddie Grogan, said Mobil's equipment may need upgrading.
"We're anticipating that they will do a full evaluation, look at their equipment and put in mitigating measures in the near future."
Mr Grogan said the council was investigating the equipment used and why it failed.
Mobil New Zealand lead country manager Andrew McNaught said yesterday that the company apologised for the incident.
Mr McNaught said it was working as quickly as possible to manage the situation, in order to minimise environmental damage.
Mobil spokesperson Samantha Potts said only trace fuel oil was now left on the water and technical experts were investigating what went wrong.
"We certainly will be reviewing the integrity of all our pipework," she said.
"Obviously the safety of our operations is of the utmost priority. We will want to ensure that the parts are safe and the terminal is fully operational."