Fuel removal from the sunken New Zealand navy ship HMNZS Manawanui which ran aground in Samoa last month is almost underway.

The New Zealand Defence Force said in its latest update that its contract with the salvor was almost finalised and the ship's main fuel tanks remain intact.

Commodore Andrew Brown said removing the fuel would be a complex task and it signalled the next phase in the recovery.

"Once the fuel removal contract has been finalised, the salvor will be mobilising equipment and personnel to Samoa to remove the fuel and other pollutants from the ship."

Brown said Samoan authorities have signed off on the methodology.

Navy personnel have been assigned to help with removing fuel, and the Defence Force said it will remain in Samoa until all aspects of Manawanui's recovery were complete.

The recovery process has been underway since the navy vessel sank after hitting a reef in Samoa in early October.

The 75 passengers and crew onboard were evacuated into life rafts in a move that authorities said likely prevented loss of life.

In the weeks that followed, concerns were raised about the environmental impact of the sunken vessel, with the ship's fuel tanks a primary focus of concern.

Residents had been reporting an oil-like substance and rubbish in the water around the wreck, and local conservationists have called for its removal in order to preserve the delicate ecosystem.

Last month, a warning was issued to residents on the southwest coast of Upolu, telling them not to eat fish from the area, and Samoan government representatives have called for financial compensation from Wellington.

The New Zealand Defence Force has said [. https://www.rnz.co.nz/international/pacific-news/532554/salvage-company-assessing-how-to-extract-fuel-from-manawanui removing the fuel tanks was a priority], and its teams on the ground were focused on protecting the environment.

Three shipping containers that came to rest on the coral reef, and were causing significant damage were removed by the end of October.

Commodore Brown said it was a complex task that took four days to complete.

"The containers were a priority ... because they were moving on the reef," he said.

Interim Court of Inquiry report into HMNZS Manawanui sinking received

Chief of Navy Rear Admiral Garin Golding said they had received the interim Court of Inquiry reporting into the sinking of the HMNZS Manawanui.

He said the court had made good progress with its investigations and was on track with evidence gathering.

The interim report was directed on what happened, but the final report would look at why the incident occurred and what lessons could be learnt, he said.

"The interim report will also undergo an independent King's Counsel legal review, and following that, we will look to release to the public later this month some of the key information about what happened."

The final report is expected to be completed around the end of February and to be released to the public by late March after it has been subjected to an independent legal review.