White Island eruption: 'We are at the hands of the sea' - Police say both missing victims were washed out to sea

Police say it's believed both of the two people who remain unaccounted for following the devastating White Island eruption have  been "washed out to sea".

Forty-year-old Hayden Marshall-Inman of Whakatane and 17-year-old Winona Langford of Australia remain missing.

Deputy Police Commissioner Mike Clement says it's believed the pair are no longer on the island.

"It is my strong view, but I cannot be absolutely positive, that the two bodies - Winona Langford and Hayden Inman - were washed out to sea," Clement told reporters on Wednesday.

At the time of the eruption, 47 people were on the island - 16 of whom are confirmed dead.

Clement told reporters the two missing bodies could be near East Cape.

"What we can say is there's no guarantee that a body caught in that tidal pattern would end up at landfall," he said. "In fact, it could just as easily be carried over top of the East Cape and out to the Southern Ocean."

Clement said they are not giving up the search.

He said one of the bodies, believed to be that of Hayden Marshall-Inman, was spotted two days after the eruption but couldn't be recovered.

Marshall-Inman's brother Mark Inman told Newshub on Tuesday if authorities had gone to White Island earlier, he believes Hayden's body would have been found.

"It is tough - but you've got to stay strong and stay positive and keep hoping one day he'll come home," Mark said, adding it was still a waiting game.