Tourists could be seen waiting to be evacuated from White Island. Image: BBC News

Thirty-four people survived, with 31 still receiving treatment in hospital.

Two British women were among those receiving treatment, said the UK High Commissioner to New Zealand, Laura Clarke.

Australian Prime Minister Scott Morrison said he "feared" three of the five confirmed dead were Australian.

Mr Morrison said that 24 Australians were on board a cruise ship exploring the island in the Bay of Plenty when the volcano erupted. Of those, 13 people had been hospitalised and 11 were unaccounted for, he said.

"This is a terrible tragedy, a time of great innocence and joy interrupted by the horror of that eruption," Mr Morrison told reporters in Sydney.

Also among those listed as missing or injured were US, Chinese, Malaysian and New Zealand citizens.

New Zealand Prime Minister Jacinda Ardern said at a press conference on Tuesday that she shared the "unfathomable grief" of those who had lost loved ones.

Tourists were seen walking inside the crater of White Island volcano moments before it erupted. Ms Ardern said further rescue efforts for the missing were now "very sadly a recovery operation".

The survivors of the eruption were taken off the uninhabited island by boat or by helicopter. Emergency services have so far been unable to search the area because of dangerous conditions, with plumes of smoke and ash continuing to rise above the volcano on Tuesday.

Ms Ardern acknowledged the apparently high number of Australian victims. "Can I say to our Australian family, there are no two countries closer and we are devastated at what has happened here and particularly want to acknowledge those from Australia who have been caught up in this horrific, horrific incident," she said.

White Island, also called Whakaari, is the country's most active volcano. Despite that, the privately owned island is a tourist destination with frequent day tours and scenic flights available.