A further 80-odd tonnes of oil has been pumped off Rena, so a total of 337 tonnes has now been taken off the container ship grounded off the coast of Tauranga.
An estimated 1000 tonnes of oil is still on board the Rena.[image:3440:half:right]
Maritime New Zealand says the oil transfer had to be stopped for three hours during the night because a pump had to be repositioned in the number five port fuel tank.
The pumping of oil also stopped on Sunday afternoon while a second pump, with a wider hose attached, was lowered into the tank to increase the flow rate.
Maritime New Zealand says once the second system in the port tank is going, salvors will look to start pumping oil out of settling tanks in the container ship's engine room.
A fresh oil leak was discovered during an observation flight on Sunday morning over the Astrolabe Reef where the ship has been stuck since 5 October.
Up to 350 tonnes of oil has spilt into the sea since then, but until Sunday morning there had been no significant leaks for 12 days.
The authority says between 5 and 10 tonnes of oil seeped into the water overnight, probably from the ship's duct keel, a tunnel at the bottom of the ship which connects the fuel tanks.
It says trajectory modelling shows the oil will head north from the vessel and there is a possibility it will reach Mayor Island.
Maritime New Zealand says four vessels placed booms around oil from the ship after the overnight leak.
Svitzer Salvage on Sunday said the situation did not seem to be serious but any oil in the water needed to be taken seriously.
The salvage teams are looking at options to speed up the transfer of oil off the ship however Svitzer Salvage spokesperson Matt Watson says the faster oil is pumped the more risky the operation becomes.
Maritime New Zealand says the heavy tug boat Go Canopus has been brought to Tauranga to help in the operation and will be fitted with oil tanks.
The boat has a large anchor so it can be used if the weather gets too rough for the bunker barge Awanuia which has so far been used.
Maritime New Zealand salvage adviser Captain John Walker says the Go Canopus has flexibility to move around and face the weather as it comes in, whereas the Awanuia is anchored in one position off the stern.
However, he says the large tug boat will not be able to stay close to the Rena during really bad weather.