Heavy oil spill and strong winds hit the vessel for a second day on Wednesday, sending empty containers dropping off the ship, which is leaning at around 18 degrees, into the heaving seas. About 50 seabirds have died and group of naturalists have scrubbed and treated 20 more for oil pollution.
The captain was charged with "operating a vessel in a manner causing unnecessary danger or risk". The 775ft (236m) Rena ran aground on a graphed reef off the North Island port of Tauranga a week ago. Officials say the fuel oil leaking from the ship has caused the country's worst environmental disaster in decades.
Maritime New Zealand (MNZ), which is managing the emergency response, said about 70 containers had fallen off the Rena after more bad weather overnight shifted the vessel into a heavy list. The ship is carrying 11 containers of hazardous materials, MNZ said, including ferrosilicon which is flammable upon contact with water.
MNZ said the hazardous materials containers were not among those that had fallen overboard. But New Zealand Prime Minister John Key said stress fractures had been found on the Rena. He said "we can't rule out the risk of the ship breaking up, that's certainly being monitored".