Rescuers were digging through dirt and parts of a collapsed road tunnel on Monday to reach 40 workers trapped by a landslide at a construction project in northern India.

All of the construction workers are safe, police officer Prashant Kumar said, adding that they have been supplied with oxygen and water. He said the rescuers had established contact with the trapped individuals.

The collapse occurred on Sunday in Uttarakhand, a mountainous state dotted with Hindu temples that attract many pilgrims and tourists.

Rescuers outside a collapsed road tunnel where at least 40 workers were trapped by a landslide in northern in Uttarakhand, India. Photo / AP

Massive construction of buildings and roadways has taken place in recent years in Uttarakhand. The trapped workers were building part of the Chardham all-weather road, a flagship federal government project connecting various Hindu pilgrimage sites.

Rescuers outside a collapsed road tunnel where at least 40 workers were trapped by a landslide in Uttarakhand, India. Photo / AP

The number of trapped workers was confirmed on Monday by Rajesh Pawar, project manager at Navyug Construction Company, which is overseeing the construction of the tunnel.

Rescue efforts began on Sunday, with authorities pumping oxygen through a pipe into the collapsed section of the tunnel to help workers breathe.

“The team has progressed 15 metres into the tunnel, with an additional 35 metres yet to cover,” Kumar said, adding that more than 150 rescuers had used drilling equipment and excavators to clear debris through the night.

The collapsed portion of the 4.5-kilometre tunnel is about 200 metres from the entrance, officials told the Press Trust of India news agency.

In January, Uttarakhand state authorities moved hundreds of people to temporary shelters after a temple collapsed and cracks appeared in over 600 houses because of the sinking of land in and around the town of Joshimath in the region.