An independent investigation into the Whakaari / White Island disaster is inevitable and necessary to answers the questions of New Zealanders and overseas tourists, Opposition leader Simon Bridges says.
Prime Minister Jacinda Ardern this week stopped short of announcing a Government probe into the eruption that killed at least 16, saying officials would be providing advice on the issue after the summer break.
Ardern said any probe would only fill gaps between two investigations already currently being carried out by health and safety watchdog Worksafe and the coroner.
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National Party leader Bridges on Tuesday told reporters the PM was being "unduly reticent".
"There will inevitably be those questions about whether tourists should have been on that island at this time, what the future of that tourism looks like, whether the recovery was done well," Bridges said.
"These are the sort of things New Zealanders and the international community will want to see there has been an independent inquiry on."
Bridges said it was also important to have a probe that was free of Government departments.
"As sure as night follows day, there will need to be an independent inquiry," he said.
Meanwhile, Australian Foreign Affairs Minister Marise Payne, speaking in Auckland, would not be drawn on whether Australia expected a further probe.
Of those killed, 10 are Australian citizens - as is one of the two people whose bodies have yet to be recovered – and Payne has been in New Zealand to meet Prime Minister Jacinda Ardern, visit hospitals and touch base with rescuers and officials.
"If it becomes subject of inquiry it would not be helpful for me to make gratuitous comments about that," Payne said.
"My absolute focus here is on the victims and their families. New Zealand will pursue its own inquiries."
Payne choked back tears as she spoke of the victims.
"I cannot begin to imagine what those families are facing in the coming days and months," she said.
"They face tragedy and devastation and our hearts and thoughts are with them."
Australian officials who had been helping with the victim identification process had now returned home, while consular staff were still providing assistance, Payne said.
"I regard this is truly as an A-NZ effort," she told reporters.
Ardern on Monday told media the Worksafe probe would cover questions of public safety and the obligations of tourism operators during the event, and could lead to prosecutions.
That investigation was now expected to take up to a year, she said.
She also said there also needed to be a separate look into the emergency response to the eruption, but suggested that would likely be handled by police.