Copiapo, Chile, Aug. 07, 2010 : Rescuers struggled on Friday to reach 34 miners trapped deep inside a small copper and gold mine in northern Chile after a cave-in, hoping miners took refuge in an underground shelter with oxygen and water.

Officials had no details about those trapped on Thursday in the mine located 28 miles (45 km) from the northern city of Copiapo and 450 miles (725 km) north of the capital, Santiago, but said they could survive for days in the shelter.

Mine owner Compania Minera San Esteban Primera said it was unclear what caused the collapse at the underground mine located in Chile’s arid northern Atacama region.

Distraught relatives hugged, cried, prayed and shouted angrily near the mine entrance as workers erected a plastic tent with makeshift beds for them.

“We want the company to show its face. Someone has to take responsibility for these 34 lives,” Maria Valenzuela, 45, whose brother-in-law is trapped inside the mine, shouted at Chile’s visiting labor minister. “We are anxious and impatient.”

The accident shut down the mine, which is one of three sites adjacent producing a combined 1,200 metric tons of refined copper annually.

The closure is not expected to hurt copper output in the world’s No.1 copper producer. Major mining accidents are uncommon in Chile, because authorities keep strict controls over operations.

But local union representative Felix Medina told  that conditions in many smaller mines in the area are precarious and Mining Minister Laurence Golborne was warned of the situation in a recent meeting.

Golborne, who is returning from Ecuador, said he had sent his undersecretary and other officials to the accident site.

“At the moment, we have no details on the workers’ condition. We assume that conditions will allow them to be rescued soon,” Golborne told .

“Once the crisis is over, we are going to evaluate the causes and origins of this collapse,” he added.

Isabel Allende, senator for the northern Atacama region, visited the area and said Congress would investigate the incident.

The region’s superintendent, Ximena Matas, said the miners could have huddled in a shelter that contained oxygen and food and believed air was flowing into the mine.

“We understand that there is ventilation and the shelter should provide oxygen for 72 hours,” said Matas.

She said rescuers had found several cave-ins and were trying to clear air shafts to try and reach those trapped around 7 km (4.5 miles) inside the winding mine using ropes.

Medina said the mine employs 150 and has a recent history of accidents, with 13 fatalities on site and three deaths on the winding road to Copiapo.

“This is an area with a lot of mining activity but the authorities don’t have the resources for proper supervision,” said the union leader.

He added that the mine lacks escape routes and was closed in 2005 by workers because of bad conditions, but it was reopened two years ago.”Unfortunately, we as workers expected this accident,” Medina said.

National emergency service ONEMI said 130 people are working on rescue efforts with five support vehicles, along with specialists for the Michilla mining company in Antofagasta, 250 miles (400 km) further to the north. The rescue has been slowed by the need to reinforce the tunnel to avoid further collapses.

“The last thing we can do is lose hope,” said 35-year-old carpenter Darwin Tapia, whose cousin is trapped in the mine. “We are praying heavily that we find them alive.”