The two missing, presumed killed by Whakaari/White Island's devastating eruption have now been confirmed as deceased by the Chief Coroner.

Whakatane local and White Island tour guide Hayden Marshall-Inman and Australian tourist Winona Langford were today confirmed to have been killed by the devastating eruption.

"The Chief Coroner has ruled that both Winona and Hayden died on Whakaari/White Island," Deputy Commissioner John Tims, National Operations Commander said.

Their bodies have not been recovered from the active volcano.

Tims' announcement brings the official death toll of the disaster to 20 people.

Eighteen of those who died after the December 9 blast died in New Zealand, with the other two in Australia.

A service for Marshall-Inman, 40, at Whakatāne's Baptist Church was attended by hundreds of people just before Christmas.

White Island tour guide Hayden Marhsll-Inman, 40, was confirmed to be deceased on Thursday. Photo / File

Brother Mark Inman told the hundreds gathered that "a moment in time" had taken Hayden.

"A moment in time has taken my brother," he told the crowd, his voice shaking with emotion.

The White Island tour guide has been remembered as a "fun uncle" and a generous person who would often leave money at the supermarket to pay for the next person's food.

Winona Langford's older brother Jesse is the only surviving member of his family after the tragedy claimed his sister, mother and father.

Winona Langford, 17, was killed along with her parents after the devastating eruption. Photo / File

Winona, 17, was exploring the area with her family when the volcano erupted.

Jesse, who remains in Sydney's Royal North Shore Hospital with serious burns, watched the funeral service for his parents and sister from his hospital bed.