A cargo ship which caused New Zealand's worst maritime pollution disaster when it ran aground three months ago broke in two in a storm on Sunday, raising fears of a fresh environmental crisis. A team of oil-spill and wildlife specialists has been mobilised as oil again began flowing from the Rena, which has been stuck on Astrolabe Reef off the North Island resort area of Tauranga since October 5. The Rena is now in two pieces which have been forced 20-30 metres (yards) apart after being pounded by waves up to seven metres high. Maritime New Zealand (MNZ) on-scene commander Alex van Wijngaarden said the National Response Team, which included oil spill response and wildlife experts was preparing for the likelihood of more oil coming ashore. "While it is unknown at this stage exactly how much oil may be released, teams have been mobilised and will be ready to respond to anything that may come ashore," he said. "The wildlife response had also been increased to help deal with any affected wildlife." 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 while an army of volunteers searched the coastline to save hundreds more. More than 1,000 tonnes of oil have since been pumped off ship but there is more on board. Salvors have also been removing containers from the vessel and said before the storm hit there were an estimated 881 still on board. MNZ salvage unit manager David Billington said the fresh damage to the ship had resulted in up to 30 containers being washed away and more were likely to be lost, with the storm not expected to ease for three days. "While the two sections of the Rena currently remain on the reef, there’s no question the ship is badly damaged with the severe movement breaking off many of the hatch covers and releasing containers from the holds," he said. Attempts were being made to tag the containers as it was too rough to tow or recover them and a navigational warning had been issued to shipping. The regional harbour master was also considering extending the three nautical mile exclusion zone set up around the Rena because of the large field of debris flowing from the ship. The Filipino captain and second officer of the Rena have been arrested and face multiple charges over the grounding, including operating a vessel in a manner causing unnecessary danger or risk. They have also been charged with attempting to pervert the course of justice, which carries a seven-year jail term, amid accusations documents were altered after the grounding. The two men are on bail but are being housed at a secret location for their own safety because of fears of a public backlash New Zealand's Environment Minister Nick Smith has claimed the Rena hit the Astrolabe Reef while taking a short cut to reach port.