The desperate effort to save 29 miners trapped underground in New Zealand remained on a knife-edge last night, as even those working to rescue the stricken men admitted that hopes for their escape were fading by the hour.
Rescue workers' frustrations were heightened when the drilling of an exploratory shaft was delayed by hard rock and a robot broke down still well short of the area where it is hoped the men have sheltered. The military robot, meant to film conditions in the mine, broke down just 500m into the tunnel.
Police superintendent Gary Knowles said: "This is a very serious situation and the longer it goes on, hope fades. We have to be realistic."
Rescuers were close to finishing drilling a shaft into the mine where the workers have been trapped for four days, with a special diamond drill just 20m and five hours away from breaking through. Hopes focused on the 500ft-long shaft down which officials planned to lower listening devices and air testing equipment.
Fears of a second explosion have delayed the rescue operation, with teams still waiting for the mine to be declared safe, and yesterday New Zealand authorities admitted for the first time that the men may be dead.
Peter Whittall, Pike River Coal's chief executive, said that the rescue crews assembled above ground were ready to go down "at a moment's notice" but that the risk was still too great. "I cannot express the frustration that our guys feel at not being able to deploy underground. It is heart-wrenching."
Mr Whittall struggled to contain his emotions as he read out the names of the 29 miners at a press conference in Greymouth, the nearest town to the mine.
As well as Peter Rodger and Malcolm Campbell, both from Scotland, the group includes a 17-year-old New Zealander, Joseph Dunbar, who was due to start work this week but had persuaded mine managers to allow him a foretaste of life underground. His mother, Pip Timms, said he was "grinning from ear to ear" when a relative dropped him at the mine on Friday.
Police – hitherto resolutely upbeat –tempered their optimism yesterday. Superintendent Gary Knowles, the head of the operation, said: "We're planning for the possible loss of life as a result of what's occurred underground."
Nothing has been heard from the 29 men since a blast, believed to have been caused by a methane build-up, sent a fireball racing through the mine. Two other workers walked out later that day, but they were only part-way into the tunnel, some distance from the others. Experts said it was possible that the latter might have found a pocket of clean air, and New Zealand's Prime Minister, John Key, refused to give up hope, insisting there was "every chance" they were still alive.