After weeks of pumping oil from Rena, a Liberian ship stranded off the east coast of New Zealand's North Island, salvage teams are still removing containers from the vessel in a desperate attempt to avoid an environmental disaster.

Each set of containers will present its own unique challenges said Arthur Jobard, the MNZ Salvage Unit Manager, This means it is impossible to predict exactly how long it will take to safely remove all of the containers on board - but realistically, it is likely to take several months of patient and careful work.

Jobard added that the Rena was still in an unstable position, which meant it was possible the vessel could break up before all containers were offloaded. If this happens, the salvagers and container retrieval company Braemar Howells are prepared to deal with the situation, he added, according to a Maritime New Zealand statement published on its Web site.

The 47,320-ton ship has been stranded on the Astrolabe reef, 12 miles from the coast of Tauranga and east of New Zealand's North Island, since October 5.

A reported 70 tons of oil has been pumped out so far, as salvage teams put in extra pumps. However, concerns over the long-term effects of the accident linger. The loss of an estimated 350 tons of oil into the sea has resulted in the death of about 1,300 birds. Environmentalists fear for more permanent damage to one of New Zealand's more pristine regions, the Bay of Plenty.

Drew Shannon, the leader of the salvage team crew, asserts that the team's current priority is minimizing the oil spill.

Steven Joyce, New Zealand's transport minister, said the Mediterranean Shipping Company will make some financial contribution.

The amount is for them to assess obviously in terms of their reputation in this country and the way New Zealanders feel about what has happened, he said.

However, the company has refused to acknowledge this comment and claimed that the ship's owner, Costamare Shipping, has to take up responsibility for the catastrophe.

Costamare Shipping has made no comments regarding the cost of disaster the company has to bear. However, the captain and the second officer have been pressed with charges of irresponsible handling of the ship.

Maritime New Zealand, the shipping industry regulator, has committed itself to the post-disaster cleanup. It has signed up nearly 8,000 volunteers for the restoration of the north coast of the island.

New Zealand's Environment Minister, Nick Smith, called the spill the country's most significant maritime environmental disaster.

With the bulk of the oil removed from the Rena and no fresh oil coming ashore, volunteers were turning their attention to removing more stubborn oil from rocky areas, said National On Scene Commander Mick Courtnell.