'I'm asking for a pardon.' The desperate request of a volcano victim's brother.

The brother of Whakaari/White Island volcano victim Hayden Marshall-Inman has written to New Zealand Prime Minister, Jacinda Ardern, requesting to stage his own mission to recover his brother’s body.

Marshall-Inman was the first victim named from Monday’s eruption, but he has not been added to the official death toll of eight, as emergency services have been unable to recover bodies from the island.

The tour guide “passed away doing the one thing he loved,” his brother Mark Inman wrote on Facebook on Monday.

Footage from Whakaari/White Island when the volcano erupted on Monday. Post continues below video.

Days on from the eruption, Marshall-Inman’s body – and those of seven others – remain on Whakaari/White Island. No recovery effort has yet been made, as police have not been satisfied the island is safe for emergency services to access.

Inman met Ardern following the disaster and later sent her office an email asking to stage his own recovery.

“With the current conditions of sunshine baking and decomposing his body, he’s going from a situation where we could have an open casket to now more likely not having a body at all – due to your government’s red tape and slow decision making,” Inman said in the email.

“I am writing to ask for a pardon for my actions of a personal recovery.”

Staff from Ardern's office responded, saying they had passed his message on to police minister Stuart Nash.

"It must be an incredibly tough time for you and your whanau. We have passed your email to the Minister of Police's office who will be in touch with you about the situation very soon."

On Wednesday night, Nash confirmed Inman's request had been denied.

"The last thing we want to do is to have further casualties in what is already a significant tragedy," Nash said.

"We won't give anyone permission to go to the island, we need to understand the risk then we can work to mitigate the chances of anyone else being injured in this."

He said he understood the request was born out of frustration, but anyone accessing Whakaari/White Island right now would be "putting themselves in greater harm".

Inman told The Project his pilot friend Tom Storey, who was part of the rescue efforts directly after the eruption on Monday, had seen his brother's body and moved it onto a rise.

"We all know health and safety is important, but when health and safety starts to become a barrier to retrieval, that's when you get frustrated," Inman said.

Storey told The Project about the rescue effort, saying "The things I remember I probably don’t want to remember but I’m probably going to remember them for the rest of my life".

Despite geological monitoring predicting a 40 to 60 per cent chance of another eruption on White Island in the next 24 hours, operations commander Mike Clement said his emergency committee were working on options for retrieval.

"The options will be in the range of - get in quick, uplift the bodies and get out as quickly as you can - because that makes sense to everybody, right?" he said. "But there's a consequence or a trade-off for that.

"One of the disciplines associated with uplifting deceased people in mass casualty situations is preserving the evidence that might lead to identification. The more time we can spend with the body when we uplift it form the circumstances in which they've died, the more likelihood we can preserve that evidence.

"We'll get no thanks whatsoever if we reach a situation at the end of this where we're not able to find identities. That would be a poor outcome for us. They're all trade-off situations. That's my job, to consider the options."

GNS Science, New Zealand's primary monitoring agency, downgraded the alert level from three to two on Thursday but noted that was a reflection that an eruption was not currently occurring.

Another GNS volcanologist, Brad Scott, said the seismic activity on Whakaari was hugely stronger than it was before Monday's deadly eruption.

"The seismic activity that started at 4 o'clock yesterday morning and carried on ramping up yesterday and throughout the night... (and) we're recording this morning, is a factor of 12 stronger than before the eruption occurred on Monday," Scott told TVNZ.

The death of two people in hospitals overnight has swollen the official death toll from Monday's blast to eight.

The further eight people located on White Island have yet to be added to that grim tally.

Dozens more are currently receiving care in four burns units around New Zealand.

-With AAP.

Feature image: Facebook/Twitter @TheProject_NZ.