New Zealand police have admitted for the first time that lives could have been lost in the Pike River coal mine, where 29 miners haven’t been heard of since an explosion on Friday afternoon.

“We still remain optimistic, we are still keeping an open mind, but we are planning for all outcomes and…also under this process we are planning for the possible loss of life as a result of what has occurred underground,” Superintendent Gary Knowles told a press briefing at Greymouth this evening (NZ time).

It was still too dangerous for a rescue team to enter the mine, because of the possibility of heating underground, he said.

Reports from experts indicate there is still heating in the mine that may ignite and samples of the gas in the mine are being taken every half hour. Cameras and listening devices may also be lowered into the mine.

Mr Knowles said officials needed to establish “beyond reasonable doubt” that conditions were safe to enter.

He said preparations were also being made to insert a robot into the mine.

Meanwhile, Beaconsfield mine survivor Brant Webb told Radio New Zealand the situation at Pike River was “horrible”, but it would be worse for the rescuers above the surface.

“Miners will do anything for their fellow miners … they must be going insane up there,” Brant, who spent two weeks trapped in a Tasmanian mine in 2006, said.

“We just hope and pray and really feel for the families.”