Giving evidence under cross-examination at the inquiry into the deaths of the 29 men who died in November last year, assistant commissioner Grant Nicholls said he was unaware of a report by the New Zealand Mines Rescue Service which stated it was unlikely that anyone would have survived the blast.

Police upheld the possibility of survival for a number of days after the initial explosion, unaware of the report which contradicted their optimism.

The commission heard the possibility of survival was in fact very slim, according to a report filed by Seamus Devlin from the New South Wales Mines Rescue Services.

“In my opinion it is almost certain that death occurred if not immediately then within the first hour of the first explosion on the 19th of November 2010,” Devlin said.

“My experience at other mine disasters is that the initial shockwave or related gases would have led to rapid extinction of life.”

Nicholls admitted to the commission that his assumptions of survival were based on an accumulation of advice and the escape of two men from the mine.

“Well I think it’s only fair to say that we relied on Mr Whittall [Pike River Coal chief executive Peter Whittall],” Nicholls said.

“There was a lot of hope. I've explained that. And there was a lot of information to consider.

“I thought that they could’ve survived and I held that view based on all the available information to me, but having reflected, I think that the men died fairly quickly, in a very short space of time,” he added.

The commission heard that the police were not informed of this information because the Mines Rescue Service was not part of the rescue’s risk assessment decisions.

Nicholls then defended claims made by Mines Rescue Service lawyer Garth Gallaway about the competency the police had in leading the rescue mission when they were not equipped to go underground, saying that it was accepted for them to take charge in a crisis situation.

Nicholls brought to light obvious flaws in the recovery effort, admitting at no time did police commanders consult with expert mines rescuers on the risks associated with recovering the men.

"It was police, police and up to police … that's how all communication was done,” Nicholls said.

“Order had to be brought to a very chaotic situation, so this was a period of where decisive action had to be taken.”

Nicholls said decision making processes would involve multiple agencies if a similar disaster occurred.

Earlier in the day, Nicholls admitted that most of his knowledge of the Mines Rescue Service came from a Google search.

Solid Energy lawyer Craig Stevens went on to suggest the police did not act quickly enough in their decisions, pointing to the delay in sealing the mine which could have prevented the second explosion.

“Experts had suggested sealing the mine portal while maintaining a flow of compressed air to a fresh air base where survivors could have been gathered,” Stevens said.

"You could have sealed the mine but still preserved life in it,” he said.

Nicholls dismissed the accusations, saying sealing the mine would have created a situation where “life was no longer a viable option”

The second explosion at Pike River on November 24 started a fire which caused the roof of the mine to collapse.