A cargo ship stranded on a New Zealand reef for the past three months has split in two in a severe storm, creating fears of a fresh oil spill, maritime officials said on Sunday.
The two pieces of the Rena have been forced 20-30 metres apart after waves of up to six metres hit the vessel, Maritime New Zealand spokesman Ross Henderson said.
"The National Response Team has been activated to respond to the potential release of oil from the ship and to treat any affected wildlife," he said.
The Rena has been stuck on Astrolabe Reef off the North Island resort area of Tauranga since October 5 and salvors have been in the process of removing more than 1,000 containers from the vessel.
Henderson said the forward section of the ship remained in its original position on the reef and while the stern was also still on the reef it was "moving significantly".
When the Rena ran aground, about 350 tonnes of oil spilled into the sea and was washed on to once-pristine beaches, killing at least 1,300 birds.
More than 1,000 tonnes of oil have since been pumped off ship but there is more on board.
The Filipino captain and second officer of the ship face multiple charges over the incident, including operating a vessel in a manner causing unnecessary danger or risk and attempting to pervert the course of justice.
Before the storm hit, 389 containers had been removed from the Rena, 98 had been washed overboard and an estimated 881 remained on the ship.
Henderson said there had been a "significant discharge of containers and container debris" during the storm and a three-kilometre exclusion zone around the stricken ship may have to be extended.
New Zealand's environment minister Nick Smith has claimed the Rena hit the Astrolabe Reef while taking a short cut to reach port.