White Island eruption: Hayden Marshall-Inman's brother vows to 'keep fighting' to get body back

The brother of a tour guide who died in the White Island eruption says despite communication from authorities being "appalling", he will continue to fight to return to the island.

Mark Inman, whose brother Hayden Marshall-Inman remains on White Island, is urging police to begin their recovery efforts immediately. 

"The longer we leave the situation, the worse the bodies are getting," Inman told The AM Show on Thursday. "You've gone from a situation where my brother was recognisable to a state [of] who knows now, with the conditions out there. God only knows what the other bodies are turning into."

Inman wrote a letter to Prime Minister Jacinda Ardern asking for a "pardon" so he could go back to the island and recover his brother. In the letter, he said if the Government would not recover his brother's body then he would do it himself.

But Police Minister Stuart Nash declined the request, saying the island is not stable and that he isn't willing to risk lives.

"We will not give anyone permission to go to the island," Nash said at a late-night press conference on Wednesday. 

Inman says Nash's decision is disappointing, especially given the fact that local experts have deemed a recovery effort possible.

"We sit back and we have faith in the authorities and we have faith in our experts' expertise [but] two of the most knowledgable [are] willing to go out and help and have offered their services and no one wants to take it on board," Inman told The AM Show.

"The way the current decisions are being made I don't believe we'll get any of the bodies back because they'll never let us back on the island."

He says "two perfect opportunities" to recover the bodies have already been missed.

"What faith do you have left in authorities when you've got volunteers who are willing to go out and help the locals and the other international tourists who are out there and bring them home to their loved ones?"

Despite the lack of action, he said he would continue to push police to act.

"Until we get that body back, we'll keep fighting."

Scientists are warning of increased seismic activity on the island, and say there is a chance of another eruption in the next 24 hours. However, on Wednesday GNS admitted that in hindsight a recovery effort could have gone ahead on Tuesday.

Inman says if authorities wait until there is no risk of eruption the bodies will never be recovered.

"You go back over the last 30 years, every day there's the likelihood of an eruption - how's it any different?"

"Here we are making decisions based on risk analysis, well somebody in OSH is never going to give you a 50/50 call and say that's ok, because they don't want that on their own mind," Inman said.

"At some point, you've got to get some common sense."

Despite his frustration, Inman said he had no plans on going back to the island without police permission, out of respect for the families of other victims.

"Until I can meet the other families and seek their permission then I can't go out there and touch anybody else's body - that's just not the right thing to be done," he said.

"As much as I'd love to get my brother back, you still have to trust in the process for now, until you reach a breaking point."