The HMNZS Manawanui, aground in Samoa. Photo: Supplied / Profile Boats
Authorities in Samoa say 200,000 litres of diesel has leaked from the Manawanui since it sank on a reef last week.
The New Zealand navy ship ran aground, caught fire and sank off the south coast of Upolu in Samoa earlier this month.
The HMNZS Manawanui - a specialist dive and hydrographic vessel - had been conducting a reef survey when it hit the reef.
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Samoa's Marine Pollution Advisory Committee said there was substantial damage to the reef from the Manawanui's collision and friction from its anchor.
It said the leak was at about 200,000 litres of diesel on Saturday.
RNZ Pacific reporter Susana Leiataua is in Samoa and said the damage spanned 5000 square metres but there was no sign of oil contamination on the reef and coastline.
The Manawanui was lying about 35 metres below the water off the coast of Tafitoala, according to the committee's latest report on the sinking and its aftermath.
The commander of a British warship supporting the recovery effort said he could not see any sign of fuel spills or debris from the sunken vessel from his position, about two miles (3.2km) away.
"Out where I am, I'm about two miles off the reef, which you'll understand we don't want to get in too close, but we have seen no evidence of any oil spills or any further debris," HMS Tamar commanding officer Tom Gell said.
"But clearly I can't comment on closer in, and I know that there's a significant effort to make sure that's fully understood."
His crew would do whatever it could to help the New Zealand Defence Force and Samoan government dealing with the Manawanui, he said.
Committee chairperson Fui Tupai Mau Simanu told RNZ divers were at the site to gather more information and to stop the fuel leaking.
Ultimately, the plan was to remove the remaining fuel from the Manawanui, he said.
Chief of Navy, rear admiral Garin Golding, told Morning Report some 950 tonnes of diesel fuel were onboard the Manawanui when it sank. The fuel is a lighter oil which can partially evaporate, leaving long-chain hydrocarbons that are relatively less toxic.
Sources had suggested to RNZ concerns had been raised about potential oil leakage from the ship's engine before it left.
Golding was asked to provide assurance the ship was fully operational, with no concerns about maintenance prior to leaving.
"The ship was in a maintenance period," he said. "It conducted that, they did trials post that maintenance period, and the ship was determined safe to deploy for their operation."
RNZ is expected to speak with Commodore Andrew Brown, the Defence Force's Deputy Chief of Navy, in Samoa later on Saturday.
