They are a hardy type in Ahaura. As might be expected of those living in a town on the remote west coast of New Zealand's South Island, the locals pride themselves on their resilience and ability to cope with adversity.

But as they waited to learn the fate of 29 men who have not been heard of since an explosion ripped through the Pike River coalmine, many in the close-knit community were fearing the worst.

The local mayor, Tony Kokshoorn, has briefed the families of the missing men, who include two Britons. He said they were "grief stricken" by a disaster that has touched the entire community. "There's a little bit of anger, there's a little bit of despair," Kokshoorn said. "There's tension building all around. People aren't talking about the worst, but I can see it on their faces.

"One of my councillors, he's down there [in the mine]," Kokshoorn said. "There was a young guy that just got the rugby league player of the region last week; he's down there. There's a local publican, real popular fellow; his son's down there. There's a woman I talked to; her husband's down there, they've got five young kids. It's right across the board. It's just devastating."

Local police have insisted that they "remain positive" the men will be found alive. But so far they have been unable to send in rescuers because the area has not been declared safe.

A local union representative, Trevor Bolderson, warned that the chances of a second blast were high. "Gas samples taken at the mine are turning the wrong way and we are expecting that the second explosion may be forthcoming," he said. "At the moment the rescue guys can't get into the mine because of this."

New Zealand's prime minister, John Key, said ministers and officials were "doing what we can to make sure these 29 brave men are taken out of the mine and are here in one piece".

Both missing Britons are believed to be Scottish. One, Pete Rodger, 40, from Perthshire, emigrated to New Zealand two years ago to be closer to his mother and sister, according to Scotland's Courier newspaper. Malcolm Campbell, originally from St Andrews in Fife, is the second. The 25-year-old miner is due to marry his fiancee, Amanda Shields, 23, next month.

His parents, Malcolm and Jane, were waiting in hope for news of their son. "We can't concentrate on anything, we can't sleep because it's difficult," Malcolm said. "Our prayers and thoughts go out to everybody who is going through this in New Zealand. We just keep hoping that everything will be fine."

News of the disaster, which is likely to have been caused by methane gas, emerged after two miners stumbled to the surface hours after a blast shot up the mine's 108-metre ventilation shaft.

But since then Peter Whittall, chief executive of Pike River Coal, said nothing had been heard from the 16 employees and 13 contract miners who are known to be trapped below.

Only one underground communications link is working, an emergency phone that rescuers have been calling constantly without success.

Whittall suggested the miners, aged from 17 to 62 and including a South African and two Australians, might be trapped in an area away from the phone, or are reluctant 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."

Australia's prime minister, Julia Gillard, said her country was ready to help. Chile, where 33 men were rescued last month after spending a record 69 days trapped underground, is also offering support.

Whittall said it would be easier to make a rescue attempt at Pike River than it had been in Chile. The colliery's main shaft is a horizontal tunnel, enabling easy access by foot or heavy vehicle. Rescuers will start to drill a hole to check if teams can enter the area safely. A drill rig has been mobilised and would try to sink a small hole to a depth of 100m-150m, to test gas levels and the threat of more explosions. It could take 16 to 20 hours. "If we can make the hole big enough, we have some opportunities to put other devices into the mine," Whittall said.

Pike River, the only publicly listed coalmine in New Zealand, has operated since 2008, excavating a 2.3km seam containing an estimated 58.5m tonnes of coal, the largest-known deposit of hard coking coal in the country.

But the mine has suffered from technical problems that have affected production targets and forced management to renegotiate with their backers. Professor Dennis Buchanan, a mining expert at Imperial College London, said that coalmines remained "by far the most dangerous environments to work in" because of the problems associated with a build-up of methane gas and coal dust explosions.

Buchanan said New Zealand was seen as a world leader in mining safety. "What's really surprising is this is a very modern mine in a country which has Whit stringent enforcement of all regulations," he added. "Therefore there would be a heightened awareness of this kind of risk. It's in New Zealand within a modern mine using the latest technology – in that sense it's very alarming and puzzling."

• This article was amended on Wednesday 24 November 2010. 'Ataura' was changed to 'Ahaura'.