A converted jet engine being used to smother the fire in the Pike River coal mine, continues to operate.
The 'gag' unit has been running since Wednesday night, pumping carbon dioxide into the mine to cool it and neutralise the gases inside.
It has only been shut down from time to time for essential maintenance.
A mine scientist David Cliff from the University of Queensland, says it will take a great deal more of the cooling gas to put out the fire.
Dr Cliff says it will likely be weeks before a recovery team can enter the mine.