Another explosion rocked the Pike River Coal mine near Greymouth shortly before 2pm on Sunday.
It was the fourth explosion in the mine since a blast on November 12 trapped 29 men in the mine, and another blast on Wednesday dashed any hopes that they might be found alive.
A third explosion rocked the mine on Friday afternoon, within five minutes of the time of the first explosion which led to the tragedy.
There were no injuries from today's explosion and people working near the entrance to the mine were moved away from the area for their safety.
Superintendent Dave Cliff said the latest explosion demonstrated the volatility of the environment surrounding the mine.
``Our focus continues to be on the safety of those people working at the mine site and the recovery team.
``We are doing all we can to progress the recovery operation, however the explosion reinforces the risks involved in working in this environment and the requirement to put people's safety first.''
NZPA was told that today's explosion blew away some of the infrastructure on top of the shaft.