While the recovery of bodies was a priority, other people could not be put in danger, according to Acting Assistant Commissioner Bruce Bird.
"We cannot put other people in jeopardy to go out there until we're absolutely certain that the island is actually safe," Bird said at a press conference in Whakatane, located some 50 km away from the volcanic island Whakaari (also known as White Island), in the northeast of the country, reprted Efe news.
On Wednesday, geological activity control group GeoNet warned that volcanic activity on Whakaari Island had increased significantly, and that the alert level remained at 3 on a scale of 5.
A total of 47 people, mostly tourists, were on the uninhabited island when the volcano erupted on Monday afternoon with the expulsion of rocks and a large ash cloud.
Six of these 47 people have been confirmed dead and eight remain missing on the island with virtually no chance of being found alive.
Authorities have attempted access to the island following the Whakaari eruption, but security conditions on the ground have prevented teams from being sent.
While New Zealand authorities attempt to identify the bodies, 30 others people remain hospitalised, most of them with severe burns in more than 30 percent of the body and respiratory problems from the inhalation of gas and ash.
The last fatality was reported late Tuesday from among the group of injured rescued from the island.
Doctors have not ruled out the possibility of others too succumbing to their injuries from burns.
Some of the survivors were yet to be identified due to the severity of the injuries, Police Minister Stuart Nash told state broadcaster Radio New Zealand.
"There are a number of people in hospital who cannot communicate because they have significant burns not only to skin but to internal organs," said Nash.
Among the 47 affected were tourists of various nationalities: 24 Austral, nine Americans, five New Zealanders, four Germans, two Britons, two Chinese and one Malaysian.
( With inputs from IANS )