Moment Royal New Zealand Navy vessel catches fire and sinks

This is the moment a Royal New Zealand Navy vessel catches fire and sinks after running aground on coral reef off Samoa, leaving crew members on board shipwrecked.

The New Zealand Defence Force said on Sunday the HMNZS Manawanui - New Zealand navy's specialist dive and hydrographic vessel - ran aground near the southern coast of Samoa's main island of Upolu on Saturday night.

The 75 crew and passengers on board had been carrying out a tropical reef survey at the island nation before the vessel caught fire and sank on Sunday morning at 9am.

Samoa fire commissioner Tanuvasa Petone said the ship erupted in flames before going down following a successful rescue mission - with all on board reported safe ashore, NZ Radio declared.

Three of the 75 needed hospital treatment, he added.

'They're all on land. They are safe and sound apart from just a few individuals that… have some minor injuries, and so we treated them at the site and transferred to them to the hospital.' 

Rescue operations were coordinated by Samoan emergency services and Australian Defence personnel with the assistance of the New Zealand rescue centre, according to a statement from Samoa Police, Prison and Corrections Service posted on Facebook. 

Several vessels responded and assisted in rescuing the crew and passengers who had left the ship in lifeboats, Commodore Shane Arndell, the maritime component commander of the New Zealand Defence Force, said in a statement.

A Royal New Zealand Air Force P-8A Poseidon was also deployed to assist in the rescue.

Video and photos published on local media showed the Manawanui, which cost the New Zealand government around £48million in 2018, listing heavily and with plumes of thick grey smoke rising after it ran aground. 

The cause of the grounding remains unknown and requires further investigation, the Defence Force said following the incident.

Samoan authorities had issued a marine warning for the island's south coast over the weekend.

Winds of up to 25mph and ocean swells of up to 13ft were forecast around the time of the incident.

The New Zealand military said rescuers had battled currents and winds that pushed the life rafts and sea boats toward the reefs and 'swells made the rescue effort particularly challenging.'

It added it was 'working with authorities to understand the implications and minimise the environmental impacts'. 

Defence Minister Judith Collins described the grounding as a 'really challenging for everybody on board.'

'I know that what has happened is going to take quite a bit of time to process,' Collins told the press conference.

'I look forward to pinpointing the cause so that we can learn from it and avoid a repeat,' she said, adding that an immediate focus was to salvage 'what is left' of the vessel.

Chief of Navy Rear Admiral Garin Golding told a press conference in Auckland that a plane would leave for Samoa on Sunday to bring the rescued crew and passengers back to New Zealand. 

He said some of those rescued had suffered minor injuries, including from walking across a reef. 

The Manawanui has conducted a range of specialist diving, salvage and survey tasks around New Zealand and across the South West Pacific.

It was also used for marine salvage and featured a 100-tonne sea crane. 

New Zealand's Navy is already working at reduced capacity with three of its nine ships idle due to personnel shortage.