Deputy police commissioner Mike Clement said there was "every chance" the bodies had been washed into the sea from the stream where they were last seen Monday.

He added that searchers were "satisfied that the area we searched near the jetty is clear of the bodies".

"The rescue teams are frustrated. We understand completely how frustrating it is for loved ones who want the bodies back," Clement said.

Forty-seven people were on the island -- a popular tourist attraction -- when the explosion happened.

The death toll now stands at 18 after an Australian victim who had been repatriated to Sydney died in hospital almost a week after the deadly eruption.

Another 26 survivors remain in New Zealand and Australian hospitals, of which at least 18 are listed as "critical" and fighting for their lives after the eruption on the desolate island, which is the country's most active volcano.

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