Police have launched a health and safety investigation into the deaths of at least six people after a volcanic eruption in New Zealand.

Officers launched the probe after an explosion on White Island killed six, left 30 injured and eight others missing and presumed dead on Monday.

Questions have now been raised as to why they were allowed onto the island after geologists had noticed volcanic activity.

There are no more signs of life on the volcanic island, also known as Whakaari, top officials said after the eruption.

More than two dozen of the injured suffered massive burns across up to 71 per cent of their bodies and could yet die of their wounds, said Peter Watson, the government’s chief medical officer.

Police said 47 people were on the uninhabited island at the time of the eruption – 24 from Australia, nine from the US, five from New Zealand, four from Germany, two each from China and the UK and one from Malaysia.

New Zealand volcano: Eruption in photos Show all 20 1 /20 New Zealand volcano: Eruption in photos New Zealand volcano: Eruption in photos Smoke from the volcanic eruption of Whakaari, also known as White Island. New Zealand police said the blast had left five people dead, but that number will now rise to include those people who were still on the island when it erupted allessandrokauffmann via Reuters New Zealand volcano: Eruption in photos Emergency services attend to an injured person TVNZ via Reuters New Zealand volcano: Eruption in photos Thick smoke from the volcanic eruption SCH via Reuters New Zealand volcano: Eruption in photos The volcano on New Zealand's White Island spewing steam and ash moments after it erupted Michael Schade/AFP via Getty New Zealand volcano: Eruption in photos White Island Tour operators rescuing people minutes after the volcano erupted Michael Schade/AFP via Getty New Zealand volcano: Eruption in photos Thick smoke from the volcanic eruption from a distance of a vessel SCH via Reuters New Zealand volcano: Eruption in photos An aerial photo shows White Island after its volcanic eruption New Zealand Herald via AP New Zealand volcano: Eruption in photos An aerial view shows smoke bellowing above the crater of Whakaari GNS Science via Reuters New Zealand volcano: Eruption in photos Emergency services attend to an injured person arriving at the Whakatane Airfield New Zealand Herald via AP New Zealand volcano: Eruption in photos This handout photograph courtesy of Michael Schade shows the volcano on New Zealand's White Island spewing steam and ash minutes following an eruption on December 9, 2019. - New Zealand police said at least one person was killed and more fatalities were likely, after an island volcano popular with tourists erupted on December 9 leaving dozens stranded. (Photo by Handout / Michael Schade / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / MICHAEL SCHADE" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS == NO ARCHIVE (Photo by HANDOUT/Michael Schade/AFP via Getty Images) HANDOUT Michael Schade/AFP via Getty New Zealand volcano: Eruption in photos A wreckage of a helicopter amid ash minutes after the volcano on New Zealand's White Island erupted Michael Schade/AFP via Getty New Zealand volcano: Eruption in photos SCH via Reuters SCH via Reuters New Zealand volcano: Eruption in photos This image released by GNS Science, shows plumes of smoke from a volcanic eruption on White Island, seen from Whakatane, New Zealand Monday, Dec. 9, 2019. A volcano erupted Monday on a small New Zealand island frequented by tourists, and a number of people were missing and injured after the eruption. (GNS Science via AP) GNS Science via AP New Zealand volcano: Eruption in photos An aerial view shows smoke bellowing above the crater of Whakaari, also known as White Island, volcano as it erupts in New Zealand, December 9, 2019, in this image obtained via social media. GNS Science via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. MANDATORY CREDIT. NO RESALES. NO ARCHIVES. WATERMARKS AT SOURCE. GNS SCIENCE GNS Science via Reuters New Zealand volcano: Eruption in photos epa08056782 A handout photo made available by the New Zealand Police shows White Island (Whakaari) volcano, as it erupts, in the Bay of Plenty, New Zealand, 09 December 2019. According to police, at least five people have died in the volcanic erruption at around 2:11 pm local time on 09 December. The island is located around 40km offshore of the Bay of Plenty. EPA/NEW ZEALAND POLICE HANDOUT BEST QUALITY AVAILABLE MANDATORY CREDIT HANDOUT EDITORIAL USE ONLY/NO SALES NEW ZEALAND POLICE HANDOUT EPA New Zealand volcano: Eruption in photos An aerial view shows hikers walking on the crater rim of Whakaari, also known as White Island, shortly before the volcano erupted GNS Science via Reuters New Zealand volcano: Eruption in photos Emergency services at Whakatane Airport Getty Images New Zealand volcano: Eruption in photos A rescue helicopter arrving at the airport Getty Images New Zealand volcano: Eruption in photos White Island (Whakaari) volcano, as it erupts Michael Schade/EPA New Zealand volcano: Eruption in photos White Island (Whakaari) volcano, shortly before erupting Michael Schade/EPA

Jacinda Ardern, the prime minister, told New Zealand’s parliament: “The scale of this tragedy is devastating.”

Police officers are now preparing to conduct drone flights over Whakaari to scout the island in advance of manned landings.

“We understand people’s desire to recover their loved ones and we are working around the clock to get onto the island so we can recover them as soon as possible,” a statement read.

Officers added: “At this time police are investigating the death of the individuals on Whakaari/White Island on behalf of the coroner.

“To correct an earlier statement, it is too early to confirm whether there will also be a criminal investigation.

“WorkSafe New Zealand has opened a health and safety investigation into the harm and loss of life caused by the eruption.

“As the workplace health and safety regulator and administrator of the adventure activities regulations, WorkSafe will be investigating and considering all of the relevant work health and safety issues surrounding this tragic event.”

Ms Ardern has said the government will also investigate how tourist excursions to the volcano were allowed to take place, as geologists said “heightened activity” had been observed on Whakaari recently.

“There will be bigger questions in relation to this event. These questions must be asked and they must be answered,” she said.

Drexel University volcanologist Loyc Vanderkluysen ​said on Monday: “I have to say that I’m very surprised to hear there were visitors there today, because scientists seem to have been well aware that White Island was entering a phase of heightened activity.”