A robot will probably be sent into a New Zealand coal mine where 29 men have been trapped for nearly three days as toxic gas delays the start of a rescue operation, a district mayor said on Monday.
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 on Friday afternoon, with authorities saying the gas level made it too dangerous to enter the mine.
Progress was being made, Grey District mayor Tony Kokshoorn told Reuters, with a robot being prepared to be sent in to the mine on Monday afternoon to check whether there was a clear path for rescuers once the go ahead to enter is given.
"They're sending a robot in," Kokshoorn told Reuters.
"There's an obstacle or a truck that's parked in the tunnel itself, but they've been assured by the driver that there's a meter on each side and they can move around that, so they'll be getting some vision with the robot."
Efforts were now being made to try to ensure the robot was spark resistant to avoid the risk of a new gas explosion, one source told Reuters.
Drilling started on a 15 cm (six inch) ventilation shaft on a steep hillside above the mine on Sunday evening, and Kokshoorn said this was going "brilliantly," having gone about 100 meters of the 162 meter estimated depth to the mine.
Once the shaft is drilled rescuers are hoping to lower a camera down to determine if the men are nearby.
"Things are moving forward," Kokshoorn said.
An explosion of naturally occurring methane gas is thought to have caused the explosion. High levels of gas have been detected near mine ventilation shafts.
Authorities have said that it is possible that the miners have survived the blast and are in an area where the air is cleaner.
Tests on the air quality are being conducted every 30 minutes at the mine's shafts, but the toxic gas levels have been fluctuating. They needed to be falling to allow rescue teams to go in.
Families and friends of the trapped men have been briefed on the progress, and emotions in the small town of Greymouth, the closest to the mine site, are running high.
"My message is we have to hang onto hope....The most important thing now is we don't make a ham-fisted attempt at rescue," New Zealand Prime Minister John Key told Sky News TV.
The trapped men range in age from 17 to 62 and include two Britons, two Australians and a South African. Two men escaped from the mine after the blast with moderate injuries.
The weather in the mountains in which the mine is situated was generally fine and sunny for the first time in several days.
The isolated mine has been dug about 2.3 km (1.4 miles) horizontally into a mountain range, with the trapped men believed to be most of the way inside. There are ventilation shafts climbing vertically at least 100 meters to the surface to provide fresh air, and a compressed air line is still being pumped in.
Thirty rescuers, including Australian experts, are ready to go, but it's been estimated that it would take them around two hours to walk over the uneven ground and through dark, smoke-filled tunnels.