A senior rescue authority in New Zealand has said work is ongoing to determine if conditions in a coal mine are safe enough to send in rescue crews.
Authorities are still drilling a bore hole and planning to use a robot to search for the 29 men trapped in the coal mine since Friday, as frustration grows over the slow pace of a rescue hampered by the risk of toxic, flammable gases.
There has been no contact with the miners since an explosion ripped through the Pike River colliery on the rugged west coast of New Zealand's South Island, with authorities saying high gas levels are preventing rescuers from entering.
Speaking at a press conference, Tasman Police District Commander Superintendent Gary Knowles said: "We still remain optimistic, we're still keeping an open mind but we are planning for all outcomes and this also part of this process, we planning for the possible loss of life as a result of what's occurred underground and we're keeping an open mind and we are planning for that."
Anger and frustration has been growing over the stalled rescue, with New Zealand authorities being questioned over the preparedness of a mining industry thought to be among the most safety-conscious in the world to cope with such a disaster.
Special equipment to measure and analyse gas levels has been flown in from Australia, and seismic equipment was also to be used to search for any signs of life.
Drilling of a 15 cm-diameter shaft on a steep hillside above the mine has been underway since Sunday night and is now believed to have reached two-thirds of the estimated 162 metre depth to the main mine shaft, which is dug horizontally into the side of a mountain range.
It is expected to break through to the mine shaft on Monday afternoon, and authorities hope to send down a camera and laser imaging equipment to look for any sign of the men, and a tube to constantly monitor the air quality.
Officials have refused to speculate whether the men are still alive after being trapped with no food and, it is believed, limited water.
