A frantic battle to rescue 41 construction workers trapped in a tunnel in northern India has faced fresh delays due to a problem with a drilling machine, with officials warning that the next 24 hours could be critical to their chances of survival.

The workers have been trapped beneath a collapsed road tunnel in the Uttarkashi district of India's Uttarakhand state for 12 days after a portion of it collapsed due to a landslide.

The platform on which the U.S.-made auger machine has been mounted became destabilized after developing cracks, according to the Times of India.

The 25-ton platform is being reinforced with concrete with drilling expected to resume later on Friday.

A crane carrying a drilling machine during a rescue mission for trapped workers in India

A crane carries a part of a drilling machine being used to rescue construction workers in India. The platform on which the U.S.-made Auger machine has been mounted became destabilized after developing cracks. (Arun Sankar/AFP via Getty Images)

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The machine is being used to drill through the debris in order to create an escape route consisting of a tunnel of pipes welded together. Once it is in place, rescue teams hope the workers can escape to freedom. 

The plan is to wheel the workers out on stretchers through the pipes, according to the BBC.

The auger machine has a drilling capacity of up to 16 feet per hour and is equipped with a 2.9-foot diameter pipe to clear debris. At times, drilling is slowed down by the pile of rubble. 

Rescue teams are required to drill down about 195 feet to reach the trapped workers. They are currently about 30 feet away and in the final phase of the operation.

Rescue personnel in India prepare to enter into a tunnel where 41 workers are trapped

Rescue personnel prepare to enter the tunnel. (Arun Sankar/AFP via Getty Images)

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The construction workers have been trapped since Nov. 12 when a landslide caused a portion of the 2.7-mile Silkyara tunnel they were building to collapse about 500 feet from the entrance. The hilly area is prone to landslide and subsidence.

The workers had been helping to construct a section of a 424-mile road connecting various Hindu pilgrimage sites in the area. The mountainous topography has several Hindu temples that attract pilgrims and tourists.

Shortly after the collapse, rescue personnel were able to establish contact with the workers, and they have been able to send them oxygen, food and water.

A view of a collapsed tunnerl where 41 workers are trappe in India

A view of the entrance to the collapsed tunnel in the Uttarkashi district of India's Uttarakhand state. Rescue efforts have been delayed due to a problem with a drilling machine. (Arun Sankar/AFP via Getty Images)

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It is the latest setback in the rescue operation.

The operation was stalled on Wednesday after workers encountered a thick metal rod, which had to be cut using gas cutters, the BBC reported.

Officials commandeered the U.S. machine last week after the initial one they were using was too slow at pushing through the debris.

The Associated Press contributed to this report.