New Delhi | The National Disaster Management Authority on Saturday said that rescue operations at the Silkyara tunnel may take time with the auger machine facing repeated troubles and the focus is now on vertical drilling to bring out the 41 trapped workers.

Briefing the media on the progress of rescue operations, NDMA member Lt Gen (retd) Syed Ata Hasnain said that "it will take time" to bring out the trapped workers as everything has to be done with utmost care.

The focus is now on vertical drilling and the operations may start in the "next 24 to 36 hours" as machines are being placed on a platform on top of the tunnel, the member said.

About 86 meters of vertical drilling is needed to reach the crust of the tunnel, and thereafter it will be broken to reach the trapped workers, he said.

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

The NDMA member further said a very difficult operation is going on. Two methods are being used currently, but a third method that is drift method could also be used soon.

Currently, 47-meter horizontal drilling has been completed, he said, adding the broken part of the auger machine has to be removed, and the drilled structure has to be kept stable.

Drilling at the collapsed portion of the tunnel to rescue the trapped men was halted again on Friday night after the auger drilling machine engaged in drilling through the rubble faced a hurdle, apparently a metal object.

Uttarakhand Chief Minister Pushkar Singh Dhami on Saturday said that the blades of the auger machine have got stuck in the rubble.

International tunnelling expert Arnold Dix said the auger machine has busted with rescuers considering other options, including vertical and manual drilling, to bring out the trapped workers.