Hopes for the imminent rescue of 41 men trapped in a highway tunnel in the Indian Himalayas for nearly two weeks have been dashed by a problem with the drilling equipment, officials say, but efforts to reach the workers should resume soon. The men, construction workers from some of India's poorest states, have been confined in the 4.5km tunnel 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. Attempts to pull them out by drilling through the debris of rock, stones and metal and pushing through an evacuation pipe have been slowed by snags. Rescuers had hoped to finish the drilling late on Thursday but had to suspend it after the platform on which the auger machine is placed was damaged, and subsequently a metal pipe was found stuck to the machine, requiring it to be reassembled, a government statement said. An estimated 15 metres of debris was left to be drilled through and a study using ground penetration radar showed there was no metallic obstruction for the next 5m, said Bhaskar Khulbe, a senior tunnel project official. "We have a very big positive in that," Khulbe told reporters on Friday. "This means our drilling should be smooth ... and we are much more hopeful," he said, adding that drilling should resume by 11.30am (5pm AEDT). 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 second plan to drill vertically from atop the hill was also being pursued and the drilling machines were 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 bread, lentils and mixed vegetable curry. More than a dozen doctors, including psychiatrists, have been at the site, talking to the men and monitoring their health. The collapsed tunnel is on the Char Dham pilgrimage route and aims to link four key Hindu pilgrimage sites with 890km of two-lane road. Authorities have not said what caused the tunnel collapse, but the region is prone to landslides, earthquakes and floods. with AP Australian Associated Press