An Australian mine safety expert and a former senior NZ public servant have been named as Royal Commissioners in the Pike River mine tragedy inquiry.

Herald deputy business editor Grant Bradley, who has visited the Pike River mine and covered the company for the Business Herald, on why today's receivership move by Pike River was inevitable.

Pike River Coal Ltd, the owner of Pike River mine, has been put into receivership.

State-owned coal miner Solid Energy's plans to turn low-grade Southland lignite coal deposits into massive new industries make no sense and the coal should remain in the ground, says the Parliamentary Commissioner for the Environment.

The fire which has been raging for days at the Pike River Coal mine is definitely out, say Australians brought in to operate the GAG jet unit which has been pumping carbon dioxide into the mine.

Pike River Coal will have to reduce its workforce when it is ready to re-establish operations, but CEO Peter Whittall says reports of possible receivership were "extremely premature".

Pike River has rejected claims management was not approachable for staff with safety concerns before the November 19 blast.

Firefighters were last night battling to cool the extremely hot concrete pad around the Pike River mine vent shaft.

An operation has begun to extinguish the fire coming from the vent shaft of the Pike River mine and cool the surrounding concrete pad, using water pumped up from a nearby creek.

Balloons replaced candles as the birthday of one of the Pike River Mine 29 was celebrated yesterday in the first individual memorial service.