New Zealand shipping authorities Monday continued pumping fuel from a stricken cargo ship stuck on a reef off the east of the North Island as worsening weather threatened to bring the operation to a halt.

Oil streams from the Rena.?[Agencies]

Since late Sunday, about 74 tonnes of oil had been pumped from the 47,000-tonne Rena, which has been grounded on the Astrolabe Reef since Oct. 5, according to Maritime New Zealand (MNZ).

And MNZ officials denied reports that the fully-laden Liberian- flagged ship is breaking up on the reef, which is about 12 nautical miles offshore near the port of Tauranga.

Salvage experts advised that while the Rena had wide cracks port and starboard, it remained in one piece and in the same position it had been for the past week, said an MNZ statement.

MNZ salvage unit manager Andrew Berry said Monday that oil pumping operations were continuing to go well, and a booster pump was in place and expected to start operating soon.

"All going well, this will increase our pumping capacity, and we will be continuing to pump oil for as long as we possibly can today. However, the operation is still very much dependent upon a number of factors, such as weather, equipment, vessel stability and other considerations, which will have an impact upon how well this process goes," Berry told the media.

"The key point is that every drop of oil that we can get off the ship is one less drop that can potentially end up in the environment, but it will be a long, slow and steady process."

However, the forecast weather for northerly winds and rain was expected to bring swells of up to 2 meters.

MNZ salvage coordinator Bruce Anderson said he expected more containers and oil to leak from the Rena and it was possible the back half of the ship will come off.

He said warming equipment was needed to heat the fuel so it was less viscous and easier to pump out.

The vessel, owned by Greek company Costamare Shipping, was carrying 1,700 tonnes of fuel and more than 1,300 containers when it hit the reef en route from Napier to Tauranga.

About 350 tonnes of oil has spilled from the ship, killing hundreds of sea birds and endangering seals and other wildlife.

Svitzer Salvage spokesperson Matt Watson told Radio New Zealand there was a risk the vessel could break up if the weather deteriorated.

MNZ volunteer coordinator Bruce Fraser said about 5,500 volunteers had signed up to assist with spill clean-up, and local businesses were offering accommodation, food, drink, equipment, and more.

"We'd like to thank the people of Bay of Plenty and further afield who have signed up to be volunteers or are working in different areas of the response. We also want to acknowledge the fantastic support of local businesses. It's fantastic to see this kind of community spirit shining through," said Fraser.

The unfolding environmental disaster has spurred protests against plans for further exploration for deep sea oil in New Zealand waters.

On Monday, activists with the environmental group Greenpeace protested near Port Taranaki, in New Zealand's oil and gas hub of New Plymouth, against an exploration ship that was due to start operations.

"Greenpeace are here conducting a legal peaceful protest to expose the fact that even as oil continues to seep from the wreck of Rena, the government is pushing ahead with the next phase of their controversial deep sea oil drilling plans," said Greenpeace campaigner Simon Boxer.

A statement from Greenpeace said the organization had been dealing with a surge of public interest after the Rena spill, with "thousands of New Zealanders" signing its "No New Oil" petition over the last week, bringing the total signatories to more than 92, 000.

The Petroleum Exploration and Production Association of New Zealand (PEPANZ) described calls for a moratorium on exploration and production as a "misguided and misdirected" response to the Rena disaster, which would suspend an industry worth 2 billion NZ dollars (1.6 billion U.S. dollars) a year to the nation's GDP and 1 billion NZ dollars in taxes.

John Pfahlert, PEPANZ executive officer, said the country could not afford to ban shipping, and nor could it afford to ban oil and gas production.

"No one is seriously suggesting banning maritime shipping, because as an island nation we need sea transport moving goods in, out and around the country. Equally we cannot afford to ban oil and gas production, because this is a vital sector for the New Zealand economy, producing jobs and revenue that will be at risk with an arbitrary ban."