SILKYARA, India, Nov 25 — Rescuing 41 workers trapped in a highway tunnel in the Indian Himalayas for two weeks will take much longer than previously hoped as rescuers are switching to manual drilling following damage to machinery, officials said today.

The heavy drill brought in to break through nearly 60 meters of debris was damaged yesterday and was being pulled out entirely, government officials said, adding the last 10-15 metres would have to be broken with hand-held power tools.

The men, construction workers from some of India’s poorest states, have been stuck in the 4.5-km tunnel being built in Uttarakhand state since it caved in early on November 12.

Authorities have said they are safe, with access to light, oxygen, food, water and medicines.

A heavy drill machine, called an auger, which got damaged after hitting an obstacle yesterday, broke while being pulled out of the 47-meter pipe inserted to bring out the trapped workers.

Pushkar Singh Dhami, chief minister of Uttarakhand state said today the damaged drilling machine would be taken out by tomorrow morning, allowing manual drilling to start.

Syed Ata Hasnain, a member of the National Disaster Management Authority which is overseeing rescue efforts, said the operation was becoming "more complex” and the process would become slower, compared to when the auger was used to drill.

"We have to strengthen our brothers stuck inside. We need to monitor their psychological state, because this operation can go on for a very long time,” he said, without giving a timeline.

Today morning the trapped workers, all migrants, were "very worried”, said Sunita Hembrom, whose brother-in-law Birendra Kishku, 39, is in the tunnel.

"My brother in law told me that he has hasn’t eaten any food since yesterday. We are very worried,” she said.

Authorities have not said what caused the tunnel collapse, but the region is prone to landslides, earthquakes and floods.

The tunnel did not have an emergency exit and was built through a geological fault, a member of a panel of experts investigating the disaster said on Friday on condition of anonymity as they are not authorised to speak to media.

The rescue plan involves pushing a pipe wide enough to pull the trapped men out on wheeled stretchers. Rescue workers rehearsed the evacuation by going into the pipe and being pulled out on stretchers, a video clip provided by the authorities showed.

A second plan to drill vertically from atop the hill is also being pursued and the drilling machines are being assembled, the statement said.

The men have been getting cooked food since a larger lifeline pipe was pushed through earlier this week and the statement said they were sent 200 rotis or Indian round flat bread, lentils and vegetable curry.

More than a dozen doctors, including psychiatrists, have been at the site, talking to the men and monitoring their health.

They have been advised to do light yoga exercises, walk around in the 2-km space they have been confined to, and to keep speaking to each other. Rohit Gondwal, a psychiatrist, said they were also considering sending in playing cards and board games.

The collapsed tunnel is on the Char Dham pilgrimage route, one of the most ambitious projects of Prime Minister Narendra Modi’s government.

It aims to link four key Hindu pilgrimage sites with 890 km of two-lane road, at a cost of US$1.5 billion (RM7.02 billion). — Reuters