Recovery teams are making good progress in the effort to stabilise the Pike River Coal mine where the bodies of 29 workers remain, police say.
There have been a series of explosions at the West Coast mine which began on 19 November and the operation has been further hampered by a coal fire that has been burning since Sunday.
A machine designed to make the mine safe to enter was started at 10.30pm on Wednesday. The GAG machine is a modified jet engine that will pump nitrogen into the mine to neutralise explosive gases.
The officer in charge of the recovery operation, Superintendent Gary Knowles, says the team has been testing the air inside the mine on Thursday and there are signs that the environment is beginning to stabilise.
Mr Knowles says Pike River Coal is building a lid to cap the shaft once the mine is inert to starve the fire of oxygen and snuff it out. This is expected to take weeks rather than days.
Forensic dentists and DNA experts are on stand-by in the event that the remains of the workers can eventually be brought out.
Mr Knowles says all activity at the mine stopped for two minutes at 2pm to honour the men, but the work of degassing the mine resumed immediately and will continue 24 hours a day.
Pike River Coal chief executive Peter Whittall says there is enough fuel and water for the GAG machine to run continuously and it is a matter of waiting to see how the air in the mine reacts to the inert gases being pumped in.
In Greymouth, thousands of people attended a national service of remembrance to honour the men who died. Other services were held around the country.
