Indian rescuers are considering opening a vertical shaft to free 41 men trapped in a collapsed tunnel after drilling at the site was paused over fears of further cave-ins and as efforts stretched into a second week.
Excavators have been removing earth, concrete and rubble from the under-construction tunnel in the northern Himalayan state of Uttarakhand since last Sunday after a portion of the tunnel collapsed.
Rescue efforts have been slowed by continued falling debris as well as repeated breakdowns of the crucial heavy drilling machines, with the air force having to twice airlift in new kit.
Drilling through the tonnes of debris was paused late Friday, after a cracking sound created a "panic situation", officials said.
Operations were then halted due to the possibility of "further collapse", said the government's highways and infrastructure company, NHIDCL.
"Every possible effort is being made," Minister of Road Transport Nitin Gadkari said Sunday, after visiting the site.
He said if the drilling machine was fixed, they could reach the men by Tuesday, but said teams were also considering multiple alternative routes.
Relatives of those trapped, who spoke to the men via radio, said conditions were grim and morale low.
"They are in tears... they have started asking us whether we are lying about the rescue efforts being made to save them," one relative told reporters late Saturday, without giving their name.
- 'Bring those 41 men home' -
Engineers had been trying to horizontally drive a steel pipe about 90 centimetres wide through the debris -- enough for the increasingly desperate trapped men to squeeze through.
Bhaskar Khulbe, a senior government official involved in the rescue operations, said teams were now considering digging an entirely new shaft, including from above.
That could involve digging down more than 100 metres, but a track would have to be constructed to even bring the heavy diggers to that site.
The Press Trust of India news agency reported initial "preparations to drill a vertical hole from the top of the hill" had begun, as an alternative route out.
Rescuers have been communicating with the trapped workers by radio, while food, water, oxygen and medicine have also been sent to them via a 15-centimetre-wide pipe.
Tunnel expert Arnold Dix, an independent disaster investigator and president of the International Tunnelling and Underground Space Association, said he was on his way to India after being asked to help.
"We are discussing right now our options for the safe rescue of these men," Dix told India Today.
Experts have warned about the impact of extensive construction in Uttarakhand, where large parts of the state are prone to landslides.
Dix said the tunnel was in "one of the most difficult areas", but said he was confident they would be rescued.
"We are going to bring those 41 men home," he said.
Villagers have set up a Hindu temple at the mouth of the tunnel to the local god, Boukhnag, saying the original temple had been moved during construction.
Some villagers told reporters they blamed the tunnel collapse on the fact that the initial temple was destroyed.