New Zealand Prime Minister Jacinda Ardern says she will reserve judgement over whether people should have been allowed to visit White Island, but points out that other countries also allow tourism to active volcanos.

Key points: Both the coroner and WorkSafe are carrying out investigations

Both the coroner and WorkSafe are carrying out investigations White Island previously erupted in 2016 when no visitors were present

White Island previously erupted in 2016 when no visitors were present Six bodies were recovered from the island today in a dangerous mission

Six Australians are confirmed to have died after Monday's eruption on the island and another six bodies, all believed to be Australian, have been recovered for formal identification. Two bodies remain unaccounted for.

During tours to White Island, visitors can walk to the live crater wearing gas masks, with one brochure boasting of the opportunity to see bubbling pits and steam vents up close.

Asked on ABC Radio National whether New Zealand profited from high-risk tourism, Ms Ardern said other countries offered similar experiences.

"New Zealand is not the only place in the world where people visit live volcanoes," she said.

"I say that not to trivialise the magnitude and the need to answer those very questions that you ask.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 46 seconds 46 s Prime Minister Jacinda Ardern addresses the press in the immediate aftermath of the White Island eruption.

"These are things where I wish to allow a bit of time and space for experts and proper analysis before making any judgements."

Both WorkSafe New Zealand and the coroner have opened investigations into the disaster, including whether proper risk assessments were carried out.

Ms Ardern urged people to reserve judgement until the investigations were closed.

"My view is that I need that job to be done properly," she said. "People deserve to have their questions answered."

While the police are involved in the aftermath of the disaster, due to the high death toll, Ms Ardern confirmed there was no criminal investigation.

Police were only doing "what you would expect given what has happened", Ms Ardern said.

Volcano erupted at night in 2016

Tour groups have been visiting the privately owned White Island for over 30 years. Throughout that time, the volcano warning has largely been stable at level two, Ms Ardern said.

A geologist earlier this week told the ABC that while level two was the highest alert level before an eruption took place, the violent event was "very unexpected" and few signs pointed to it.

An eruption of a similar magnitude occurred in 2016, but during evening hours when no visitors were at risk. Ms Ardern said it was her understanding that this occurred when warning levels were at one.

"It's a highly unpredictable volcano," she said, but continued "that is not sufficient in terms of explanation as to whether or not the right checks and balances were in place".

In the aftermath of Monday's eruption, tremors on the island reached similar levels to the 2016 event, preventing a recovery mission until this morning.

Six bodies were brought back from the island this morning. Eleven Australian survivors have now been repatriated to Australian hospitals, with two more expected in the coming days.

Mr Ardern said retrieving all victims from the island was a top priority.

"This is something we've wanted to undertake since Monday but conditions have been difficult," she said.

"We just want to bring everyone home."