DEHRADUN, India, Nov 19, 2023 (BSS/AFP) - 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 the workers were in 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.

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 (nearly three feet) wide through the debris -- wide 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.

"We are exploring all options to save the workers," Khulbe said late Saturday. "We have no shortage of resources, options and methods".

Khulbe said rescuers were looking at a time frame of "a maximum of four to five days" to free the men, without giving further details.

The Press Trust of India news agency reported "preparations to drill a vertical hole from the top of the hill" had begun, as an alternative route out.

Indian media carried a photograph showing an excavator starting to clear soil on the forested hilltop high above the tunnel.

Rescuers have been communicating with the trapped workers by radio, and food, water, oxygen and medicine have also been sent to them via a 15-centimetre-wide (six-inch) 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.