TAURANGA, New Zealand (AP) -- A salvage crew finally managed to board a cargo ship that has spilled hundreds of tons of oil since striking a reef off New Zealand, and workers raced Thursday to assess whether oil can be pumped from the ship before the vessel breaks up.
Several of the 88 containers that fell off the deck had washed ashore by Thursday, and authorities confirmed one container that toppled overboard contained a hazardous substance. However, an official said it should not pose a major threat.
Heavy seas had kept the team away from the 775-foot (236-meter) vessel for days, but a break in the weather allowed three crew members to be winched aboard the Liberian-flagged Rena, which ran aground Oct. 5 on Astrolabe Reef, 14 miles (22 kilometers) from Tauranga Harbour on New Zealand's North Island.
The vessel has been fractured by a large crack and has been listing in the stormy ocean.
The crew was checking the stability of the ship and whether it was even still possible to pump out the remaining oil, said Steve Jones, spokesman for Maritime New Zealand, which is managing the emergency response. Officials were trying to find out whether a heating system that is needed to liquefy the oil before it can be pumped out is still working, he said.
A vertical crack in the ship that the maritime agency described as a "substantial structural failure" runs around the entire vessel -- meaning the ship is now only held together by its internal components, Jones said.
"The reality is the vessel could break up at any point," Jones told The Associated Press. "Conditions are very calm out at the moment. ... If we're going to get oil off before the ship breaks up, today's the day."
The piles of containers that remain on deck have continued to move, making it dangerous for salvage crews to work on board. Six vessels have been mobilized to intercept the drifting containers and other debris in the water. The maritime agency has predicted more containers will topple off as the ship continues to shift.
There were 1,368 containers on board, 11 of which contained hazardous substances, Maritime New Zealand said. One of the hazardous containers is among those that have fallen overboard, Jones said.
The agency originally said the container held a substance that creates a flammable gas when mixed with water. But later Thursday, spokesman Nick Bohm said officials had made a mistake, and the container actually held alkyl sulfonic acid. The substance can be harmful in its original state, but becomes less toxic when diluted with water, he said. The whereabouts of that container are unknown.
Bernadine Walsh, a Marine New Zealand spokeswoman, confirmed that containers had washed ashore. Some of their contents were strewn across the coastline on Thursday, including thousands of meat patties that littered the sand.
The ship's 44-year-old Filipino captain was charged Wednesday with operating a vessel in a manner causing unnecessary danger or risk and was released on bail Wednesday at Tauranga District Court.
The ship's second officer appeared in the same court Thursday on the same charge. Judge Robert Wolff made orders suppressing publication of the defendants' names for the sake of their personal safety.
If convicted, each could face a fine of up to 10,000 New Zealand dollars ($7,800) and 12 months in prison. Their next court appearance is Oct. 19, when authorities say more charges are likely.
The government has demanded to know why the ship crashed into the well-charted reef in calm weather, but the vessel's owner, Greece-based Costamare Inc., has given no explanation.
On Thursday, Costamare released a statement apologizing for the incident and said it was investigating how the ship could have run aground.
"Our Captain is an experienced Master and has an exemplary record," Costamare managing director Diamantis Manos said in the statement. "The ship was fully certified and had recently been inspected ... They found no problems. Obviously something went very wrong and we will cooperate with the Transport Accident Investigation Commission of New Zealand (TAIC) to find the answer."
Maritime New Zealand estimates that at least 390 tons (350 metric tons) of heavy fuel oil have spilled from the hull, leading New Zealand's environment minister, Nick Smith, to call it the country's biggest maritime environmental disaster. Officials believe the ship had about 1,870 tons (1,700 metric tons) of oil and 220 tons (200 metric tons) of diesel on board before it started leaking.
Clumps of oil have washed up on pristine beaches near Tauranga. Maritime New Zealand said hundreds of oiled birds had been found dead and 51 others were being cleaned at a wildlife emergency center. Three seals were also being treated at the center.
Several miles (kilometers) of coastline have been closed to the public, and some beaches were beginning to experience severe oiling, Jones said.
"I was down there this morning," Jones said. "It was just black coming in -- just black, black, black."
Witnesses said dead fish were also washing ashore as local volunteers with plastic gloves and buckets worked to clean the oily clots from the white sand.