"The Police Eagle helicopter, rescue helicopter and NZDF aircraft have undertaken a number of aerial reconnaissance flights over the island since the eruption," police said in a statement early Tuesday.
"No signs of life have been seen at any point.
"Police believe that anyone who could have been taken from the island alive was rescued at the time of the evacuation.
"Based on the information we have, we do not believe there are any survivors on the island."
Australian Prime Minister Scott Morrison said last night: "We must prepare for some difficult news in the days ahead."
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Police are working urgently to confirm the exact number of those who have died, further to the five confirmed deceased already, the statement said.
"As part of the recovery a NZDF ship will approach the perimeter of the island at first light to deploy drones and observational equipment to further assess the environment.
"Police continue to receive information and advice from GeoNet experts to support the recovery operation.
"The Police Disaster Identification (DVI) team are assembling in Whakatāne to await deployment.
"Both New Zealanders and overseas tourists are believed to involved, and a number were from the Ovation of the Seas cruise ship (berthed in Tauranga).
"The police 105 number can be used by members of the public to submit information regarding friends or family who might have been visiting White Island during the eruption.
"People from overseas can call +64 9105 105.
"They can also use the online form at the police website.
"At the request of New Zealand Police, New Zealand Red Cross has activated the Family Links website for people wanting to register themselves as safe or register an inquiry about a loved one.
"If you are worried about a friend or family member following the White Island eruption, first contact them as you normally would.
"If you cannot make contact, you can register them through this website: https://familylinks.icrc.org/new-zealand/en/Pages/Home.aspx.
"The friends and family of those involved remain at front of mind for Police.
"Support is being put in place and Police are working to provide them with information as it becomes available."
Former Whakatāne mayor Tony Bonne says one of the people killed was an experienced guide for White Island Tours - "a young energetic man who's lost his life".
White Island Tours' chairman Paul Quinn said the company was deeply saddened following the significant eruption.
"Devastation is an understatement. This is a terrible tragedy and our thoughts and prayers are with everyone who has been impacted."
He said the company was currently assisting police and Civil Defence with the official emergency response.
"We acknowledge the considerable efforts from police and Civil Defence and will continue to do whatever is necessary throughout the rescue operation."
"Our immediate focus is on supporting our staff, manuhiri and respective whānau, who have been significantly impacted and are showing immense strength and courage."
A number of the tourists on the island when the eruption happened were from the Ovation of the Seas cruise ship, berthed in Tauranga.
Police have not confirmed nationalities, but there are fears for up to 24 Australians and at least three tourists from the UK.
The five people dead are people who were taken off the island on Monday.
National Operation Commander Deputy Commissioner John Tims told a press conference on Monday afternoon a number of people had burns.
He said further eruptions were possible.
Those dead are of a "range of nationalities", he said.
"The experts that we've spoken to have said it is unsafe for us to go on that island. The island is unstable ... the physical environment is unsafe for us to return to the island. It is important that we consider the health and safety of those that will return to the island.
Tims told an earlier press conference on Monday: "At this stage it is too dangerous for police and rescue to go on to the island ... the island is currently covered in ash and volcanic material.
"We know the urgency to get back to [the] island."
Nine News Australia is reporting 24 Australian citizens were on White Island when it erupted.
Tims told an earlier press conference it was believed fewer than 50 people were on or near it at the time of the eruption.
There were a number of tourists on or around the island at the time, New Zealand Prime Minister Jacinda Ardern said at an earlier press conference.
"I know that there will be a huge amount of anxiety for those who had loved ones on the island at the time."
GNS is assessing the situation at the moment and is unsure if cameras on the island are still functioning.
Dr Ken Gledhill, from GNS, said: "It's not a particularly big eruption, almost like a throat-clearing eruption, and that's probably why material won't make it to the mainland."
Smoke from the eruption went around 12,000m in the air, he said.
He said it has quietened down, but added he could not be certain there would not be another eruption in the next 24 hours.
