Trapped miners told: 'work 24 hour shifts and remove 4,000 tonnes of rock

• Spirits among the workers, who are shirtless because of the heat, remain high despite their ordeal Picture: AP

But as weeks blend into months spent in darkened solitude, the Chilean miners trapped under the Atacama Desert must retain their strength. Without it, they may not see daylight again.

As work began yesterday to drill an escape route deep into the San Jose mine, those in charge of the operation confirmed that the 33 men stranded below will need to aid their own rescue.

With vast, industrial drills breaking the earth above them, the miners will be forced to clear thousands of tonnes of rubble, an undertaking which will require them to work in shifts around the clock.

It is a Herculean task which even were it to be carried out tomorrow, would place the sternest of demands on men already hungry, emotional, and showing signs of fatigue. But such is the scale of the rescue exercise, that stage will not arrive for months to come.

With further details emerging of the logistics of the operation, it is clear that much as they depend on the engineers and specialists above, so too the miners must rely on themselves.

Such a fretful reality was acknowledged yesterday by Laurence Golborne, Chile's mining minister, who said that ensuring the men's welfare was no less vital than breaking through half a mile of rock.

"We will keep them alive, in good shape and health," he insisted. "That is something that is happening in parallel while we are digging the larger hole."

Given the sheer scale of the challenge, there are no certainties, but nearly a month on from the mine's collapse on 5 August, a considered and determined plan of action has come together.

Already, the miners have a lifeline in place, courtesy of three small boreholes created, which allow them to receive word from above, as well as food and medicine.

Such holes, comparable in diameter to a drainpipe, are now being supplemented by a single shaft. Just 26 inches wide, it will nonetheless prove large enough to usher the men to safety. One by one, the eerie journey is expected to last around an hour for each man.

Codelco, Chile's state-owned mining company, yesterday broke the earth to begin an arduous and time-consuming drill some 2,300 feet into the ground.

Once completed, it will fall upon the miners to clear the bottom of the shaft of rubble before they can escape the darkness.

Armed with wheelbarrows and industrial-sized battery-powered sweepers, it is expected that the men will have clear between 3,000 and 4,000 tonnes of rock. To do so, it is anticipated they must split into crews of six, and work in shifts 24 hours a day.

To date, it remains the best, and speediest option, albeit one which will come under intense scrutiny, given the likely deterioration in the miners' physical and mental state.

They are surviving only on the food which can be ushered through the narrow boreholes, and already, some are showing the strain.

Watching a recently released video of the men, Alberto Segovia revealed his brother, Dario, appeared to have lost more than 15 pounds during the ordeal. "He looked sad," Mr Segovia said, but "determined to survive."

Others are suffering as a consequence of the hot, humid conditions underground, with several men complaining of severe skin irritations. As a result, special clothing that dries quicker and sleeping mats have been sent below.

Laurence Golborne, Chile's mining minister, has reiterated the government's estimate of three to four months for the operation's timescale. He is mindful that the rescue process now has two distinct elements, each as vital as the other.

"We will keep them alive, in good shape and health," he explained. "That is something that is happening in parallel while we are digging the larger hole."

Mario Medina Mejia, a Chilean mining engineer, raised the issue of the miners' wellbeing with greater urgency, stressing that no matter the extent of men's resolve, it remains a finite commodity.

He said: "The question isn't whether they can safely get to the miners. It's how long can the miners wait for them to arrive."

Andrews Sougarret, Codelco's head engineer, explained that in order to create a passage large enough to spirit the men to freedom, the firm will drill a small ‘pilot hole', before vast machine cutters slowly grind through and widen it.

Normally, after completing a pilot hole, the opening would be enlarged by drilling from the bottom up, but were there a hole large enough to send the cutters to the bottom of the gold and silver mine, the men would already have made their escape through it.

Instead, the time-consuming top-down operation will require patience and delicacy, with the hydraulic bore drilling at a rate of around sixty feet a day. At one point, a decision will have to made whether to fit the newly-drilled passage with metal casing in order to prevent collapses in the walls.

It is expected to take one to two months before the first pieces of rubble fall into the shaft.

Walter Veliz Araya, the geologist who was in charge of drilling the three bore holes, believes the operation will pose no threat to the miners.

He said: "If the area where the miners are didn't get crushed in the initial collapse, drilling this new hole isn't going to do that."

Whatever happens, the resultant crushed rock has nowhere to fall but down into the mine shaft where the men have called home for the past three weeks. "The miners are going to have to take out all that material as it falls," Mr Sougarret pointed out.

Mr Golborne rejected suggestions from local engineers that alternative rescue plans could bring the men to surface earlier than expected.

He said that experts have examined no less than 10 different proposed methods, and will continue to study other options. So far though, he added, "nothing has yet been found that will be quicker."

In the meantime, work continues to make the miners' lives, if not normal, then at least bearable.

Cords of telephone wire was snaked down one of the boreholes on Sunday, allowing the men to speak to their loved ones for the first time in what was for many, a much-needed morale boost.

Thanks to medicine secreted through a borehole, one of the miners, Johnny Barrios, was able to vaccinate himself and his colleagues against tetanus and diphtheria - real and present dangers given the cramped nature of their surroundings.

Other items relayed through the narrow channels include packs of cards, MP3 players, and handheld gaming consoles, which it is hoped will provide welcome diversions for those below.