Hope survives but toxic gases threaten to halt mine rescue

Hopes for the 29 men trapped down a New Zealand mine faded last night when lethal levels of toxic gases were found close to where it was hoped they might be found.

High levels of carbon monoxide and methane were detected as trapped hot gas and air rushed up a bore hole that rescue workers managed to drill into an area near the original explosion.

Superintendent Gary Knowles, leading the operation, said conditions in the mine were so bad that it is possible that rescue workers "may never" be allowed in to search for survivors.

"The environment is still unstable, it's unsafe and it's not appropriate to send rescue teams underground," he said. "The teams want to go in but they can't. While I can understand [the families'] frustration, we are doing everything possible to go underground. Obviously over time, hopes diminish," he said.

A fire continues to burn inside the Pike River Coal Mine and while levels of toxic gases were high, readings showed there was a correspondingly low level of oxygen.

"As we expected, although not as families hoped... the air that came out of the hole was extremely high in carbon monoxide, very high in methane and fairly low in oxygen," said the mine's chief executive, Peter Whittall.

The gas readings were a further blow to relatives of the miners who have been missing since a huge explosion tore through the mine on Friday. They are thought to be trapped more than 160 metres below the surface.

Mr Whittall said after the relatives had been told of the gas readings: "There's obviously a very large understanding among the group that the gases we are finding from this borehole... the length of time... is making their hopes diminish and making it more difficult for them to hold out that hope that all 29 of those are waiting for us, as we have hoped from day one."

The gas readings came after footage from a security camera at the surface of the mine about a mile and a half from the explosion showed a cloud of white dust and stones being propelled by the force of the blast out of the entrance and across a valley. The blast, which continued for nearly a minute, was so powerful that shockwaves shooting up the mine's ventilation shaft tore off vents at the top.

Relatives of the 29 men – 24 New Zealanders, two Britons, two Australians and a South African – emerged white-faced after viewing the video and were then told that a robotic vehicle sent to search for the men had short-circuited 550 metres into the mine. It was later revealed that it had been restarted and that it had located a helmet that still had its light working. The helmet, however, belonged to Russell Smith, one of two miners who were able to walk back to the surface after the explosion.

A replacement robot vehicle was flown in yesterday by the New Zealand Defence Force, but was being modified for the conditions at Pike River, an isolated mountainside on the South Island's west coast. Two other robots are also being flown in from the United States and Western Australia.