Flowers are laid on a makeshift memorial seen in front of cruise ship Ovation of the Seas, in Tauranga, New Zealand (AP Photo/Nick Perry)
Three Australians are among the five people confirmed dead after the volcanic eruption on New Zealand's White Island, with the death toll certain to rise.
Eight people are missing presumed dead, while 13 Australians, some with critical injuries, are being treated in hospital.
Those who are fit to travel are likely to be transported to Australian hospitals as all New Zealand's burns units are full to capacity.
White Island, also known as Whakaari, erupted off New Zealand's North Island on Monday afternoon.
New Zealand police confirmed they had launched a criminal investigation into the incident, but said this was a standard procedure.
Of the 47 people on or near the island at the time, 24 were Australians aged between 17 and 72, most of whom were passengers from cruise ship Ovations of the Sea which was moored on the New Zealand mainland around 50km away.
A Sydney family of four, an Adelaide family of three and a Brisbane mum and daughter are included on the Red Cross list of those missing after the eruption.
"This is a very, very hard day for a lot of Australian families whose loved ones have been caught up in this terrible, terrible tragedy," Prime Minister Scott Morrison told reporters in Sydney on Tuesday.
"I fear there is worse news to come over the course of perhaps today or over the next few days.
"This is a terrible tragedy, a time of great innocence and joy interrupted by the horror of that eruption."
New Zealand authorities have done a reconnaissance mission and determined that nobody on the island could still be alive.
Rescuers land on White Island following the eruption of the volcano on White Island, New Zealand (Michael Schade via AP)
The full extent of the injuries suffered by the 13 injured Australians is unknown.
"At this stage it is still too early to tell - we know there are a number in critical conditions," the prime minister said.
"Obviously there are quite severe burns issues and that's why they are in so many different hospitals because they have been taken to the various burns units across New Zealand."
A forensics team from the Australian Federal Police is on its way to New Zealand to help identify victims.
Australia is also sending extra consular staff to support those affected.
New Zealand Prime Minister Jacinda Ardern addressed parliament saying "our family in Australia has been heavily impacted".
"We feel the pull of our bond acutely at this time."
The Royal Caribbean cruise company was working to help guests and authorities in any way it could, a spokeswoman said.
The company had staff on site, was communicating with guests and families, while offering medical care, counselling and accommodation, she said.
"The news from White Island is devastating. The details that are emerging are heartbreaking," the spokeswoman said.
Mr Morrison praised medical teams caring for the injured Australians.
"Some of those Australians will be a long way away from loved ones and they will be there on their own, and unaware of what has taken place because of the nature of their injuries," he said.
Australians who have concerns about the welfare of their friends and family are being urged to try and contact them directly.
Failing that, people have been told to call the Royal Caribbean cruise company or Australia's consular emergency centre.
Red Cross New Zealand has listed the people missing on its Restoring Family Links webpage, with loved ones urged to register their names.
© AAP 2019