NEARLY a week after a cave-in trapped six American coal-miners 1,800ft below ground, Utah rescuers remain uncertain whether they are alive or dead.

The drama that has gripped America over recent days has highlighted the perils of mining, an industry that has changed little in 100 years.

The hopes of many were dashed on Friday when the first drill to reach the area where the men were thought to have been working detected no signs of life and oxygen levels too low for them to have survived.

A second, larger bore broke through into the Crandall Canyon mine yesterday and a video camera was lowered to search for the miners. Mine officials kept hopes alive, saying the men could have fled to a nearby 1,000ft-long exit tunnel that could have more oxygen.

The camera found "survivable space" and an intact ceiling above the rubble, but attempts to signal the miners were met by silence. "We do have a five-and-a-half foot void. We have not lost the space where the miners could be located," said Richard Stickler, head of the US Mine Safety and Health Administration.

Families who gathered near the private mine in the Utah desert yesterday were dismayed by the slowness of the rescue mission and news that an accident at another coalmine 1,000 miles away in Indiana had killed three construction workers.

Self-described optimists such as Robert Murray, co-owner of the mine, said the men had “probably” survived the cave-in last Monday and had enough air to keep them alive until they are rescued - although that could still take days.

Former miners said the trapped men would have spent the past few days in pitch darkness, lamps switched off to conserve the batteries, without food, the only external sounds being the water leaking into the chamber and the earth shifting around them.

The grim alternative is that the miners died during the initial roof collapse. The first probe, which was 2.5 inches wide and took two days to drill down 1,500ft, initially confirmed Murray’s hope that there was methane-free air in the chamber, but later tests showed there was insufficient oxygen. Nor was there any response when the bit reached the chamber.

Residents of Huntington, a remote mining town 140 miles south of Salt Lake City, strove to remain positive.

“It may have missed the chamber where our men are. We must believe they have found a way to survive and over the next few days we shall be bringing them home,” said a city spokesman.

Another rescue mission continued to burrow through rock towards the trapped miners. Murray said he had had to rein the rescuers back because they risked further collapse if they dug too fast.

Despite their desperate efforts, the miners are able to clear only 300ft a day. Officials said that it could take another week to reach the area where the roof collapsed at 2.48am on Monday.

The 70-year-old 5,000-acre mine has received 325 safety warnings from government inspectors since 2004, including demands for more escape routes, resulting in fines of £75,000. Independent experts say that compared with other older mines it is a well run business.

Murray said the fall was caused by an earthquake, but seismologists say the only tremors they detected were caused by the cave-in itself.

Some experts believe the disaster may be related to the perilous technique of “retreat mining” used at Crandall Canyon, where columns of coal are used as props to hold up the roof rather than wooden beams. The props are removed as miners pull back along the shafts, bringing down the roof behind them.

Hundreds of wellwishers have gathered outside the mine to hold candlelit vigils and support the families.

“I am sure their lights will have died by now, so they will be sitting in pitch blackness, and it’s pretty chilly down there when you are not moving about and digging,” said Robby Robertson, 27, who used to work at the mine.

Robertson said that men work underground not just for the above-average wages, but also for the friendships forged in adverse conditions.

“It’s like war: you get closer than family. If these people are still alive. I am sure they’re sitting together, the older men being strong for the less experienced guys. They know people are trying to reach them and that hope will get them through it.”

“You try to stick together, tell stories, try to make each other laugh,” said Dennis Hall, who survived 77 hours trapped in Pennsylvania’s flooded Que-creek Mine five years ago. “We talked about sports, family and friends, school stuff and prayed to God a lot.”

Some may be following mining tradition by writing farewell notes and putting them inside their lunch boxes.

Three of the trapped men are Mexican. Hilary Gordon, mayor of Huntington, said she was communicating with the Spanish-speaking families with hugs and putting her hands over her heart. “I cannot really say it, but past experience tells us these things do not go very well,” said Gordon, whose husband is a former miner.

Others remain resolute. “All it will take is one little safe pocket where they are all tucked up. They are tough and know how to survive,” said Archibald Allred, whose cousin Kerry Allred is one of the six miners.

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