Thirty-six labourers were trapped in an under-construction mountain tunnel in Uttarkashi district of Uttarakhand after a landslide blocked their exit on Sunday morning.

Senior police officers said no deaths had been reported and that rescue teams expected to bring all of them out safely, but it might take more than a day.

The police said the labourers had entered the tunnel after 11pm on Saturday and were supposed to come out at 8am on Sunday, but a landslide inside the tunnel blocked their exit early in the morning.

“The National Disaster Response Force and other agencies are on the spot but it may take more than a day to clear the debris,” director-general of police Ashok Kumar told reporters in Dehradun on Sunday morning.

“Rescue teams are blowing oxygen into the tunnel with the help of pipes.”

Rescue operations under way in Uttarkashi. PTI picture

The 4.5km tunnel, being built as part of an all-weather road project for the Char Dham pilgrimage, lies between the villages of Silkyara and Dandalgaon.

Additional director-general of police (law and order) A.P. Anshuman said on Sunday afternoon that no deaths had been reported.

“The incident occurred around 5am, about 200 metres inside the tunnel towards Silkyara village. The labourers were working 2,800 metres inside the tunnel,” he said.

Rescue operations under way in Uttarkashi. PTI picture

Uttarkashi superintendent of police Arpan Yaduvanshi said: “Officers involved in the construction have told us that 36 labourers are trapped inside.”

Chief minister Pushkar Singh Dhami said: “I am in touch with the officers on the spot. We pray to God for the safety of all the workers.”

The Rs 1,119-crore project was conceived and approved by the Union road transport and highways ministry in February 2018. Construction was to be completed in four years.

Dhami said last month that it would be completed by March 2024. The tunnel will reduce road travel between Uttarkashi and Yamunotri by 20km.