This photo shows Monday's volcanic eruption on White Island, New Zealand. Some relatives of those who were visiting the island at the time were forced to continue waiting for news of their loved ones, with authorities deciding it remained too dangerous for crews to land on the island and remove bodies. Picture: Lillani Hopkins via AP

Wellington - Continued tremors on Wednesday have prevented police from retrieving the bodies of eight people still on New Zealand's White Island after a marine volcano erupted on Monday. 

"This is an utterly tragic situation," National Civil Defence director Sarah Stuart-Black said at a press conference. "We all agree that recovering bodies of the deceased from the island is an absolute imperative."

She added that every day that passes was anguish for loved ones, but the preservation of human life and the prevention of further human harm must be taken into account. 

Five people died after being evacuated from the island off the east coast of New Zealand's North Island on Monday and another person died on Tuesday in an Auckland hospital. 

Police said earlier that they knew from a helicopter pilot who spent some time on the island in the aftermath of the eruption that "every person on that island was not alive at that time."

GNS Science senior scientist Graham Leonard told the media on Wednesday that the risk of another eruption on White Island, also known by its Maori name Whakaari, had increased since the morning. 

A tour operator's boat to White Island is seen at the harbour in Whakatane. Picture: Jorge Silva/Reuters

Police Deputy Commissioner John Tims said police were standing by to go back to the island but it was currently too dangerous.

Tims also apologized for announcing on Tuesday that police had launched a criminal investigation into the tragedy, a comment that was later corrected as being an investigation on behalf of the coroner.

He said that police had managed to identify all of the missing and injured and would release further information shorty. 

These include 24 people from Australia, nine from the United States, five from New Zealand, four from Germany and two each from China, Britain and Malaysia.

Currently 30 patients are being treated in burn units at six hospitals around the country. Of those, 22 still remained on airway support due to the severity of their injuries.

Coroner Deborah Marshall and acting assistant police commissioner Bruce Bird address a press conference in Whakatane, New Zealand. Picture: Nick Perry/AP

Peter Watson, Counties Manukau Health's chief medical officer said they were urgently sourcing supplies to meet the demand for dressings and temporary skin grafts. 

"We anticipate we will require an additional 1.2 million square centimetres of skin for the ongoing needs of the patients," Watson said, adding that some of the patients had burns to 90 or 95 per cent of their skin.

Australian patients would soon be flown back to be treated in burn units there.