|Rescue efforts to save the 29 workers have been delayed until the Pike River coal mine is deemed safe enough [AFP]
Twenty-nine men trapped in a coal mine on New Zealand's south island are to spend a second night underground, as poisonous gases prevented authorities from launching a rescue effort.
Anguished relatives expressed frustration at the delay on Saturday, after search organisers said the levels of explosive gases were still too high to send a crew into the mine.
"If I had my way I'd be down there, I'd go into the mine myself," said Laurie Drew, whose 21-year-old son, Zen, is one of the missing men.
As he spoke to local media, Drew wore his son's jacket.
"I wore it so I can give it back to him when he comes out. I just want my boy home," he said.
The mountainous area is cordoned off - but rescue operations for the 29 missing men remain on hold
Two miners reached the surface after Friday's gas explosion, but there has been no word from the others.
Police said the miners, aged 17 to 62, are believed to be about two kilometres down the main tunnel.
There has been no communication with the missing men since an explosion rocked the Pike River colliery - the country's largest coal producer - near Greymouth on New Zealand's west coast on Friday.
Rescue leaders pledged that they would do everything they could to reach the trapped miners.
"This is a search and rescue operation, and we are going to bring these guys home," said superintendent Gary Knowles, the police search controller.
According to The explosion was likely triggered by coal gas igniting Pike River Mine Ltd, according to Peter Whittall, the chief executive.
Electricity in the mine went out shortly before the explosion and that failure may have caused ventilation problems and contributed to a buildup of gas.
The power outage continued to frustrate efforts on Saturday to pump in fresh air and make it safe for rescuers, though Whittall said air was flowing freely through a compressed air line damaged in the explosion.
"We have kept those compressors going and we are pumping fresh air into the mine somewhere. It is quite conceivable there is a large number of men sitting around the end of that open pipe waiting and wondering why we are taking our time getting to them," he said.
A working phone line to the bottom of the mine, however, had rung unanswered.
Hamish Clark a reporter from TV3 News New Zealand, told Al Jazeera that the biggest impediment to the rescue is a mixture of methane and oxygen gas trapped inside the mine, suggesting that a second coal-gas explosion is likely.
"The problem that they've got is that they can't get the gas moving through the shaft," he said. "There's no power to the mine itself, which is two and a half kilometres inside the hill," he said.
New Zealand police announced the nationalities of the trapped miners on Saturday. There are 24 New Zealanders, two British citizens, two Australians and one South African.
Three New Zealand nationals have been publically identified so far - Milton Osborne, a Greymouth district councillor, Blair Sims and Ben Rockhouse.
Australia, meanwhile, has sent a team of mine rescue experts to assist the operation.
"We know our New Zealand colleagues are doing everything they can to effect a rescue," Julia Gillard, the Australian prime minister, said in Lisbon, the Portuguese capital, where she was attending a Nato summit.
"We're waiting for further news but it could be some time yet."
William Hague, the British foreign secretary, said he was saddened to hear of the accident.
"My thoughts are with those who are missing, and also with their families and friends, who are awaiting news," he said in a statement.