WHAKATANE, NEW ZEALAND (AFP) - The official death toll from New Zealand's White Island volcano eruption rose to eight after two people died in hospital, police said on Thursday (Dec 12), with a further nine missing people presumed dead.

Officials say many more victims of Monday's explosion at the popular tourist attraction are battling to survive after suffering horrific burns.

"Two further people have died following the eruption on Whakaari/White Island, bringing the official toll to eight," police said in a statement.

"Police remain focused on supporting families at this terrible time."

Health officials said on Wednesday that 22 critically injured survivors who needed assistance breathing were in hospital burns units.

It was not immediately clear if this figure included the two most recent fatalities, who died at hospitals in Auckland and Hamilton.

Police did not release further details about the dead.

A total of 47 day-trippers and guides, hailing from Australia, the United States, Britain, China, Germany, Malaysia and New Zealand, were on the island when the blast occurred.

Seven of the nine people so far identified and named as missing by New Zealand police are from Australia.

An eighth Australian victim who died in hospital was named by the authorities there late on Wednesday.