Three Australians are feared to be among five people killed in a volcano eruption in New Zealand on Monday, Prime Minister Scott Morrison says.
Eleven Australians are still unaccounted for and 13 others have been hospitalised.
"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," Mr Morrison said in Sydney on Tuesday.
"I fear there is worse news to come over the course of perhaps today or over the next few days," Mr Morrison said.
"This is a terrible tragedy, a time of great innocence and joy interrupted by the horror of that eruption."
Thirty-one people were admitted to hospital, at least three stayed overnight.
After a frantic search for information on Monday, police now believe there were 47 people in two groups on the volcano at the time of the blast.
New Zealand authorities have done a reconnaissance mission and determined that nobody on the island could still be alive.
The extent of the injuries suffered by the 13 Australians hospitalised 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."
One group was evacuated but the other was caught out by the eruption.
There were 24 Australians caught up in the blast, all aged between 17 and 72.
A number of people from a visiting cruise ship, the Ovation of the Seas, which originated in Sydney were in the area during the unfolding tragedy.
Throughout Monday, police attempted to contact those who remained on the island during the blast without success while also trying to discover how many people were missing.
In a late-night statement, police dashed hopes of finding anyone else alive, saying ,"based on the information we have, we do not believe there are any survivors on the island."
New Zealand Prime Minister Jacinda Ardern, in the nearby town of Whakatane, confirmed six nationalities were among the 13 dead or missing: Australia, New Zealand, United States, United Kingdom, China and Malaysia.
On Tuesday morning, Acting Assistant Commissioner Bruce Bird, alongside Ardern, said it was still not safe to return to Whakaari.
"Today our focus will be on working with the experts in determining the safety for us to return to the island to look to recover those people who are currently missing," Bird said.
Australians that are still unaccounted for
Young couple James Whitehouse, 23, and Madeleine Whitehouse, 24, were holidaying in Auckland New Zealand on Monday, and have been listed as unaccounted for on the New Zealand Red Cross website Restoring Family Links.
The website allows families to register their concern for people they believe could have been caught up in the eruption.
A family-of-four from North Sydney are also among Australians who feature on the list as missing; Anthony and Kristine Langford, and their two kids Jesse, 19, and Winona, 17.
Another Australian couple yet to register their safety are Amy Miall, 30, from Brisbane and Mathew Thomas, 31, from Tamworth.
Australians listed on the Family Links site as alive include, Maree Fish from Brisbane, Eloise Kirk from NSW, and Ian Jorgensen from Penrith in NSW.
Family and friends say Whakatane tour guide Hayden Marshall-Inman was among the people killed in the New Zealand volcano disaster.
Brother Mark Inman wrote on Facebook that Marshall-Inman had passed away "doing the one thing he loved".
"Friends and family, very sad news this evening," he wrote.
"Thanks for all your messages. I'll be in touch when we know more."
The post was flooded with tributes, well-wishes and memories of Marshall-Inman, who has been celebrated as "a top man who left an impact on the world".
A local supermarket worker described Marshall-Inman's generous spirit.
"Whenever he came in and made a purchase, he always gave us $5 to pay towards the next person's groceries," Julie Lockett said.
"He had the kindest heart, it was never about him; he definitely created a ripple effect of happiness to others."
Marshall-Inman was a guide for Whakatane-based White Island Tours.
Police are yet to confirm the names or nationalities of any of the deceased.
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