Salvage teams are racing to extract oil from a leaking container ship stranded off New Zealand, ahead of forecast gale-force winds and swells.
The MV Rena has already leaked 20-30 tonnes of oil since it struck a reef in the Bay of Plenty on Wednesday.
Officials fear that if the ship breaks up in the bad weather, 1,700 tonnes of fuel could be released. Some of the oil has already reached the shore.
The Bay of Plenty is one of the country's top tourist attractions.
Oil leaking from the Liberian-flagged Rena, stranded 12 nautical miles off the coast, has created a 5km (three-mile) slick.
New Zealand's oil spill response agency, Maritime New Zealand (MNZ), said that a barge, the Awanuia, had pulled up alongside the ship and had begun pumping oil from the Rena.
"The weather is expected to deteriorate in the coming days, so we are working around the clock to remove the oil," the agency said on Sunday.
Experts say stormy weather could lead to the break-up of the Rena, as one end is stuck on the Astrolabe Reef while the other end floats free.
"The top priority is to first remove the oil, then lighten the vessel by removing the containers, and finally, move the ship off the reef," the MNZ said.
The operation is expected to last at least two days, but the bad weather could force it to delay.
Two barges have been scooping up the oil that has spilled into the sea, but the MNZ said it expected to see more oil in the water in the coming days.
Early on Monday, officials in Tauranga said oil had been been found on a beach in the city. Residents have been told to stay away from the water.
The owners of the ship, Greece-based Costamare Inc, have not given an explanation for the grounding, but said they were "co-operating fully with local authorities" to minimise any damage.
Prime Minister John Key, who flew over the scene in a helicopter on Sunday, said two inquiries to determine why the ship had collided with the Astrolabe Reef were already under way.
"People know about the reef, and for it to plough into it for no particular reason - at night, in calm waters - tells you something terrible has gone wrong and we need to understand why," he told Radio New Zealand.
The department of conservation has established two wildlife rescue centres and dispatched teams to search the beaches and islands in the area for affected animals and birds.
The maritime authorities have said a total of eight oiled birds, including little blue penguins, had been recovered and taken to a wildlife facility in Te Maunga.
"From tip to toe, they are covered in black sticky gunk, matting up all their feathers right down to the skin," said Brett Gartrell of New Zealand's Wildlife Health Centre. "They have ingested it and started to get anaemic, which is part of the toxic effect of the oil."
MNZ has established a one-kilometre maritime exclusion zone around the ship and warns that the fuel oil is toxic.
The animal welfare group Forest and Bird said the timing of the accident, in the middle of the breeding season for birds, was "disastrous".
Greenpeace said it could also affect whales and dolphins calving in the area, as well as other species.