The volcano on New Zealand's White Island spewing steam and ash  Photo: VCG

New Zealand Prime Minister Jacinda Ardern said Monday that official inquiries into last week's fatal volcano eruption could take up to a year, and will carry potential criminal penalties of up to five years in jail.

Ardern also announced a NZ$5 million ($3.2 million) fund to help small businesses affected by the eruption, after New Zealanders held a minute of silence to honor the victims a week on from the tragedy.

The official death toll from the surprise eruption on White Island, also known by its Maori name of Whakaari, stands at 16. Two people whose bodies are believed to be in the waters around the island are still officially listed as missing.

A further 26 people remain in hospitals in New Zealand and Australia, many in critical condition with severe burn injuries.

"There remains now questions to be asked and questions to be answered," Ardern told reporters in Wellington after she led the country in a minute of silence for the dead and injured, who included tourists from the US, Germany, China, Britain and Malaysia.

There has been growing criticism that people were allowed on the island, a popular destination for day-trippers, given the risks of an active volcano. That has led to speculation that the tragedy could foretell major changes for New Zealand's thrillseeker tourism economy.

WorkSafe, New Zealand's primary regulator for workplace-­related incidents, has opened a health and safety investigation, Ardern said, while the coroner is conducting a separate inquiry.

Ardern said the WorkSafe investigation could take a year, while the coronial inquiry was "also likely to continue for some time."