In order to pull out 40 workers trapped in an under-construction tunnel that collapsed three days back in Uttarakhand's Uttarkashi district, India has sought advice from a Thai company that successfully rescued children from a flooded cave in 2018, reported news agency AFP.


"Officials have contacted the Thai company which rescued the children trapped in the cave", read a statement released by the state government department of public relations.


Meanwhile, a heavy drilling machine was airlifted from Delhi Wednesday after the old equipment "failed", reported PTI, citing officials.


The new machine, that landed at Chinyalisaur, over 30 kilometres from the tunnel on the Chardham route, has been pressed into action at the site.


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However, workers at the site did not look satisfied with the progress of the multi-agency rescue operations and chanted slogans at the mouth of the tunnel protesting over the "slow" pace of the operation to rescue their colleagues.


"It is a challenging situation. We often tend to lose patience in situations like this. Our officials have spoken to the protesters and asked them not to give up patience. It may take some more time but all the trapped workers will be safely evacuated," said Uttarkashi District Magistrate Abhishek Ruhela to PTI.


The rescue team had planned to use an 'auger machine' to drill through the rubble of the collapsed tunnel and insert 800-mm and 900-mm diameter sections of mild steel pipes -- one after the other. This would have helped trapped workers to safely crawl out of the tunnel but the first drilling machine turned out to be too slow and technical issues developed.


Also, falling debris inside the tunnel damaged the equipment and injured two rescue workers on Tuesday.