Salvage experts were racing to secure a container ship which ran aground on a reef off New Zealand as oil started to wash up on Monday along beaches of a popular holiday resort.
The 47,230-tonne Liberian-flagged Rena has been stuck on the reef, about 12 nautical miles from Tauranga on the east coast of the country's North Island, since running aground early on Wednesday.
Maritime New Zealand said the weather was about to get worse.
"Seas are moderate but they will become rough later, there will be poor visibility and we are expecting showers," it said in a statement.
The ship is carrying 1,700 tonnes of heavy fuel oil, which has been transferred to secure tanks at the rear of the vessel and is slowly being pumped into a barge. Containers are being lashed more tightly.
"Salvage experts and naval architects on board are very closely monitoring the ship and have got sensors in place that will provide advance warning if the vessel's structure is coming under too much stress," Maritime NZ said.
The first oil from the ship has also been found on nearby beaches with clean up teams moving in to collect the fist-sized clumps of thick, toxic oil.
The district is a popular holiday resort, with long, golden beaches renowned for surfing, and nearby waters with an international reputation for big-game fishing.
As much as 30 tonnes of oil is estimated to have escaped from the 236-metre ship, which has been holed in two forward compartments and is listing at 10 degrees. All vents have been sealed to prevent oil escaping.
Several seabirds have died and about a dozen have been recovered and treated for oil contamination.
The ship's owners, Daina Shipping, a unit of Greece's Costamare Inc. , said minimising the pollution risk was the priority.
"The current primary focus of the salvage operations is the safe transfer of the vessel's fuel oil from her tanks into a suitable vessel," Costamare said.
Refloating and salvage of the ship, of which more than half is aground on the reef, is the responsibility of the owners and salvage experts, but any plan needs official approval.
The Port of Tauranga, 200 km (120 miles) southeast of New Zealand's biggest city, Auckland, is the country's biggest export port and a hub for transshipping cargo.