Drilling through the rubble to prepare an escape route for the 41 workers trapped at the Silkyara tunnel remained stalled on Friday morning, a day after another snag hit the rescue efforts, an official said. The platform on which the drilling machine stands was being stabilised by shotcreting, the official said.

Boring through the rubble was put on hold again Thursday apparently after cracks appeared in the platform on which the drilling machine rests, in a fresh hurdle to the rescue of workers trapped inside for 12 days.

The dampener came hours after the operation resumed earlier in the day, following a six-hour delay to cut through an iron girder that came in the way of the auger machine late Wednesday night.

This is the third time that the drilling exercise has been halted since the multi-agency rescue mission began on November 12 after a stretch of the under-construction tunnel in Uttarakhand’s Char Dham route collapsed.