Mine safety expert Associate Professor David Cliff has also arrived from Queensland and was meeting with mines, rescue and emergency services personnel at the mine to assist with the inerting process.

It was expected that further work to prepare a pad for the GAG unit to sit on would take another four hours. The mine might have to be inerted several times before the underground atmosphere is considered safe to enter with breathing apparatus.

Pike River chief executive Peter Whittall reportedly said the GAG jet engine could require up to nine hours of use to be effective.

“We may have to redeploy it again, and we may have to do it again and again, depending on what happens with the fire and how deep-seated it is,” he told the New Zealand Herald.

QMRS state manager Wayne Hartley previously told ILN it could take 4-6 hours to inert the Pike River mine the first time.

The GAG unit brought over by Queensland Mines Rescue Services is basically a jet engine which can overwhelm any fires and explosive gases underground with nitrogen, carbon dioxide and water vapour.

“The GAG has been successfully tested and it is hoped to be running today, however the mine condition is continually changing,” a statement said.

It was not possible to deploy the GAG unit yesterday because a fire started at the mine entrance when polyurethane foam used to seal the mine self-combusted.

It is now thought the fire burning in the mine after the blasts is being fed by coal as well as gas, adding to the difficulty of making the mine safe enough to enter.

The use of the GAG machine was delayed yesterday morning when polyurethane used to seal the mine portal caught fire.

The fire lasted about an hour but set back the use of the engine several hours.

With the mine already rocked by a series of explosions, the coal fire further diminishes the chances that remains of the missing miners can be retrieved.

Families are starting to come to terms with this realisation.

“Some people still have hopes of tapping on a pipe, but largely there is resignation to total loss of life and resignation for some that they may not get their family back as they want," Whittall said yesterday afternoon, according to the AAP.

Forensic experts will be called in to assist investigation efforts once the recovery effort can begin.

Thousands of people are expected to attend a national memorial service for the 29 miners at Greymouth on Thursday.

In New South Wales, Appin residents are also reportedly organising a state memorial service. A gas explosion killed 14 miners at the Appin Colliery back in 1979.