Uttarkashi | Drilling at the collapsed Silkyara tunnel to rescue 41 men trapped inside for 12 days was halted again on Friday, officials said.

Officials said the auger drilling machine faced a hurdle, apparently a metal object, soon after drilling resumed Thursday, a day after officials had put the operation on hold following a technical snag.

That snag was set right earlier in the day and the 25-tonne auger machine was restarted. But after a brief while the operation had to be stopped again in the second setback in two days.

The multi-agency rescue effort began November 12 when a portion of the under-construction tunnel on Uttarakhand's Char Dham route collapsed, trapping workers who were still inside.

Rescue workers said in the evening that the drill bit has been pulled out through the passage already bored by the machine.

Sections of steel pipes had been inserted into the bored passage to allow the trapped men to be pulled out. The effort had reached up to 48.6 metres out of the estimated 57 metres of rubble that blocks the tunnel, officials had said earlier in the day.