GREYMOUTH: New Zealand rescuers had still not made contact with 29 trapped miners on Saturday, almost 24 hours after an explosion ripped through the remote colliery dug into the side of a mountain. 

The mine’s owner said the search for the miners had been delayed while authorities ensured it was safe for rescuers to enter. Poor weather was also hampering access to the ventilation shafts, adding to the agonising wait for family and friends of the miners, who range in age from 17 to 62. 

The explosion was likely to have been caused by methane gas, Pike River Coal chief executive Peter Whittall told a news conference in Greymouth, the nearest town to the mine on the rugged South Island’s west coast. 

“The air quality tests from the samples taken this morning have been inconclusive,” Whittall told reporters, adding testing was continuing. 

“It’s a very fine balance. I’m not going to put people underground and risk further lives,” district police commander Superintendent Gary Knowles said. 

The small size of the search area in the two-year-old mine and the time to plan and prepare while the air is checked meant the actual search itself would be quick, Knowles said. 

“Once that window of opportunity opens, we only need a short timeframe to get in there, look at what’s down there, and make a decision about what we are going to do,” Knowles said. 

The miners include several Britons and Australians. 

New Zealand Prime Minister John Key said offers of help and support had flooded in from around the world. 

“This is a time of huge anxiety and concern for the miners and their families, and our hearts and thoughts go out to them,” Key said. 

Whittall said underground communications were down, except for one emergency phone which rescuers had been calling constantly without anyone picking up. 

But he stressed the miners might be trapped in an area away from the phone, or unwilling to venture from an area of safety to answer it. 

“It’s quite conceivable that there is a large number of men sitting around the end of the open (ventilation) pipe, waiting and wondering why we are taking our time to get to them,” he said. 

The accident follows the ordeal of 33 Chilean miners trapped in an underground chamber for two months before their dramatic rescue last month, when they were hoisted one by one to safety through a hole drilled 700 metres through rock. 

Whittall said the New Zealand mine gave rescuers an advantage over the Chilean situation, given the Pike River colliery’s main shaft was a horizontal tunnel, enabling easy access by foot or heavy vehicle. 

The mine is about 2.3 kilometres long, with the trapped men believed to be most of the way inside. There are a number of ventilation shafts which climb vertically at least 100 metres to the surface to provide fresh air. 

The explosion is believed to have occurred about 1.5 kilometres along the mine shaft. 

Two men escaped the mine in the moments after the blast on Friday, walking out of the main shaft, but they were unable to give rescuers the location of the others.