Superintendent Gary Knowles said the focus was still on bringing the miners out alive
Rescuers have no idea how long it might take to reach the 29 men trapped after an explosion at a New Zealand mine.
But Superintendent Gary Knowles, the head of the rescue effort at the Pike River mine, said he remained positive about finding them alive.
Unsafe levels of gases continue to make it too dangerous for rescue teams to enter the mine, officials have said.
There has been no contact with the miners and contractors since Friday’s blast at the South Island mine.
Supt Knowles said there was no “quick fix”, but that rescue workers were doing all they could to find those missing.
“We’re into day two,” he said.
“We have no idea how long this will take. But we are still focused on bringing these guys out.”
The missing workers, aged from 17 to 62, include 24 New Zealanders, two Australians, two Britons and a South African national.
Families were taken to the site on Sunday to see rescue preparations Drilling at a new shaft will begin later on Sunday to allow further tests for dangerous gases such as carbon monoxide and methane.
The local mining community is a resilient one, says the BBC’s Greg Ward in New Zealand, but the waiting process is terrible for everyone.
Local papers report a sense of despair and frustration taking hold, our correspondent says.
Tests at the mine show there are still a dangerous level of poisonous or potentially explosive gases in the mine, which rescue officials say make it unsafe for crews underground.
Mr Knowles denied suggestions rescue teams were showing a lack of urgency because they believed the chances of finding the miners alive were low.
“I find that really repugnant,” he told a press conference on Sunday.
“We’re talking about people’s lives here… My decision is made based on safety and what experts are saying.”
Safety was the priority, said Trevor Watts, head of the New Zealand Mines Rescue Service.
Employs some 150 peopleOperational since 2008Accesses Brunner and Paparoa coal seams via 2.3km tunnel under mountains5.5m-wide, 4.5m-high tunnel bisects Hawera fault, through which methane gas is known to leakBlast is believed to have happened at 1530 (0230 GMT) on FridayFears grow for trapped miners
“We have got a mines rescue member missing amongst the guys that are underground,” he said.
“And I can assure you that every rescue member working on this operation is waiting to go underground, to rescue our brothers”
“We’re a small community and we know all of those guys there. And, if there was the slightest opportunity to go underground, we will be.”
Each miner carried 30 minutes of oxygen, enough to reach oxygen stores in the mine that would allow them to survive for several days.
Fresh air is also being pumped into the mine through a shaft.
The explosion at the mine, near the coastal town of Greymouth, is thought to have happened at around 1530 (0230 GMT) on Friday.
An electrician went into the mine some twenty minutes later to investigate a power failure.
He raised the alarm when he discovered the driver of a loader who had been blown off his machine some 1,500m (4,920ft) into the shaft.
Two workers who walked out of the mine have been treated in hospital for moderate injuries but have since been discharged.
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