* NZ prime minister says no sign of life on White Island
* Eight still missing as island remains inaccessible
* Australian, US, UK, Chinese, German and Malaysian tourists on island
* Police say investigation launched, but not a criminal probe
Science agency says 50/50 chance of another explosion (Releads, adds website listing Australians in paragraph 30)
By Charlotte Greenfield
WHAKATANE, New Zealand, Dec 10 (Reuters) - Fearing the volcano could erupt again, search parties were unable to set foot on New Zealand's White Island for eight people still missing on Tuesday, after an eruption a day earlier killed at least five and injured more than 30. Prime Minister Jacinda Ardern said reconnaissance flights showed no signs of life on the ash covered island, and police doubted whether any survivors would be found, as eyewitnesses detailed the horrific burns suffered by those caught up in Monday's eruption.
"The scale of this tragedy is devastating," Ardern said in parliament. "To those who have lost or are missing family and friends, we share in your grief and sorrow and we are devastated."
Police said 47 people were on the uninhabited island, a popular sightseeing excursion for tourists, at the time of the eruption.
Twenty-four came from Australia, nine from the United States, five from New Zealand, four from Germany, two each from China and the Britain and one from Malaysia.
"I would strongly suggest that there is no one that has survived on the island," police Deputy Commissioner John Tims said of the eight people still missing.
Of the 31 injured, at least 27 suffered greater than 71% body surface burns, and some could succumb to their wounds, said Peter Watson, the government's chief medical officer.
Burns units across the South Pacific nation of 4.5 million are full to capacity, he added.
Police said an investigation into the deaths on White Island had been launched but clarified it was not a criminal investigation.
New Zealand's geological hazards agency GeoNet raised the alert level for the volcano in November because of an increase in volcanic activity. The volcano's last fatal eruption was in 1914, when it killed 12 sulphur miners.
Yet, daily tours bring more than 10,000 visitors to the privately owned island every year, marketed as "the world's most accessible active marine volcano".
"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," said Drexel University volcanologist Loijc Vanderkluysen.
"I've been to White Island before, but I don't think I would have been comfortable being there today."
A crater rim camera owned and operated by GeoNet showed one group of people walking away from the rim inside the crater just a minute before the explosion.
"It's now clear that there were two groups on the island - those who were able to be evacuated and those who were close to the eruption," Ardern said at a morning news conference in Whakatane, a town on the mainland's east coast, about 50 km (30 miles) from White Island.
Later, in parliament, she paid tribute to the pilots of four helicopters that landed on White Island in the aftermath of the eruption.
"In their immediate efforts to get people off the island, those pilots made an incredibly brave decision under extremely dangerous circumstances," Ardern said.
Since then, rescuers have been unable to access the island, which is covered in grey ash. GNS Science, New Zealand's geoscience agency, warned there was a 50/50 chance of another eruption in the coming 24 hours, as the volcano vent continued to emit "steam and mud jetting".
The Buttle family have owned the island for over 80 years, and a spokesman said they were devastated by the tragic event.
We wish to thank everyone involved in the rescue effort, including the first responders, medical personnel and the locals who helped evacuate people from the island," Peter Buttle said. "Their efforts have been both courageous and extraordinary.
Royal Caribbean confirmed several passengers on its 16-deck cruise liner, Ovation of the Seas, were on a day trip to the island but did not provide further information.
Janet Urey, 61, a nurse from Richmond, Virginia, said her son Matthew, 36, and his wife, Janet, 32, were cruise passengers injured in the eruption while on their honeymoon.
"The phone rang at midnight. Then I heard a voicemail come on. It was my son. He said, 'Mom ... this is not a joke. A volcano erupted while we were on the island. We're at the hospital with severe burns."'
Urey said she was frustrated by the lack of information from the cruise ship he was on and from authorities.
"I have not heard a word from the cruise people," she said.
A New Zealand man, Geoff Hopkins, whose tour group was just leaving the island at the time of the eruption, said he helped pull critically injured survivors into a boat.
Hopkins, 50, who was given the tour as a birthday gift, said many of the survivors had run into the sea to escape the eruption.
"People were in shorts and T-shirts so there was a lot of exposed skin that was massively burnt," he told the NZ Herald newspaper.
Australian Prime Minister Scott Morrison said three Australians were feared to be among the confirmed fatalities, with 13 among the injured.
A website managed by the New Zealand Red Cross listed 17 Australians as missing. The Family Links website is a forum for people to register missing persons, who can respond to confirm they are safe. A person who has been found but is in the hospital, for instance, might still be marked "missing" on the list.
Malaysia's high commission in New Zealand said one Malaysian was among the dead, while Britain's high commissioner to New Zealand confirmed two British women were among the injured.
Russell Clark, an intensive care paramedic with a helicopter team, said the early scenes were overwhelming.
"Everything was just blanketed in ash," he told Reuters. "It was quite an overwhelming feeling."
'Whakaari', as it is known in the Maori language, is New Zealand's most-active cone volcano, built up by continuous volcanic activity over the past 150,000 years, according to GeoNet.
(Reporting by Charlotte Greenfield in Whakatane and Praveen Menon in Wellington, additional reporting by Barbara Goldberg in New York; Writing by Jane Wardell and Raju Gopalakrishnan; Editing by Lincoln Feast, Gerry Doyle & Simon Cameron-Moore)