Rescue workers were set to begin drilling at the collapsed Silkyara tunnel Friday after putting it on hold for several hours, following a snag that delayed the operation to evacuate 41 men trapped inside for 12 days, officials said.

Officials, at an afternoon news briefing, said that the technical problem that stalled the drilling on Wednesday had been set right, and the operation would begin in the next couple of hours.

The boring would resume after the another section of steel pipes is welded to the chute already pushed through, they said.