Rescuers struggled yesterday to shore up ventilation ducts they hope can be used to reach 34 workers trapped in a mine since an underground collapse two days earlier.

More than 300 rescue workers were on scene at the San Esteban mine on the outskirts of Copiapo, in Chile’s Atacama desert.

They have yet to make contact with the 34 workers missing since the collapse, which blocked an access road to the mine, and it was unclear whether they had been able to reach an underground shelter stocked with water and food.

Labour Minister Camila Merino, who went to the site last Friday, said the shelter has provisions for about 72 hours.

Mining Minister Laurence Golborne said yesterday “five teams of eight people, 40 people in total, will drop down into openings that are between two to four square metres wide” in search of the trapped miners.

“The process of lowering into the mine is slow, it will take several hours. We will let people know if we find signs of life,” he promised.

The gold and copper mine, some 800 metres above sea level, is cut into a mountain and usually accessed by a ramp that descends in a spiral, but the collapse cut off that route, forcing workers to use the mine’s ventilation shafts, which are cut vertically into the rock.

“We really don’t know if rocks have fallen in on them or not, or whether they are alive,” mine manager Pedro Simunovic told AFP.

He said everything was ready for rescuers to start descending into the mine and he hoped the operation could be completed as quickly as possible.

A rescue worker, who declined to give his name, said it was a good sign that the air shafts were still open and unimpeded by the collapse.

“There is air, thank God the air ducts haven’t collapsed and there is still air flow,” he said.

If the miners have managed to reach an emergency shelter built into the mine, they should have enough space, food, water and oxygen for up to 72 hours, authorities said.

Relatives of the miners have gathered at the site and awaited news of their loved ones at a campsite set up by authorities, who provided them with food, mattresses and blankets against the cold nights of the Atacama desert, the driest in the world.