New Zealand's prime minister said today hope was fading for 29 coal miners missing for four days underground after an explosion.
John Key said police were now planning for the possible loss of life following the massive blast in the mine, now swirling with toxic gases.
Mr Key told parliament it was still too dangerous to enter the mine to find what had happened to the men. He said he shared the families' frustration that a rescue team could not be sent in because of the toxic gas levels in the mine.
He said the miners were tough, resourceful and stoic men who looked after each other in the same way a father looked out for a son.
Earlier the bid to rescue the miners ran into more problems when a mechanical robot broke down inside a tunnel and hard rock layers slowed progress on drilling to test the air.
Police superintendent Gary Knowles said the army robot sent in to transmit pictures and assess gas levels was damaged by water and out of commission. Authorities were urgently seeking other such robots from West Australia and the US to replace the broken one.
"I won't send people in to recover a robot if their lives are in danger," Supt Knowles said. "Toxicity is still too unstable to send rescue teams in."
Making matters worse, the drilling team boring into the mine tunnel had hit "very hard rock" overnight, he said.
Family members have expressed frustration with the pace of the response as officials acknowledge it may be too late to save the miners, who have not been heard from since the massive explosion ripped through the Pike River Mine on the country's South Island.
A build-up of methane gas is the suspected cause of the explosion. And now the presence of that gas and others - some of them believed to be coming from a smouldering fire deep underground - are delaying a rescue over fears they could still explode.
A diamond-tipped drill was put to work as workers hit layers of hard rock and came within 33ft of the tunnel where they believe some of the miners are trapped. The 500ft-long shaft they are creating will allow them to sample gas levels - including explosive methane and carbon dioxide - and determine if rescuers can finally move in days after the blast.
Supt Knowles said rescuers planned to drop a listening device down the hole to see if they could hear anything - such as tapping sounds - that might indicate that the miners were still alive.
"This is a very serious situation and the longer it goes on, hopes fade, and we have to be realistic. We will not go underground until the environment is safe," he said.
Two workers stumbled out of the mine within hours of the explosion, but there has been no contact at all with the remaining 29. A phone line deep inside the mine has rung unanswered.