At least 17 workers of a private company were buried alive and 11 injured when a portion of an underground tunnel of the Tehri hydel project caved in after heavy landslides in the area.

Nearly 50 to 60 workers, mostly labourers from Jharkhand and Bihar, were working inside the tunnel when boulders and unused construction material hurtled down on them on Monday night, District Magistrate Punit Kansal said.

Thirteen bodies have been recovered and efforts are on to recover the remaining, Tehri Hydro Development Corporation Executive Director R D Prabhakar said.

THDC officials said 20 to 30 people could still be under the debris.

The authorities are preparing a list of the labourers who were working at the time of the incident.

The 260.5 metre high Tehri dam, the highest in Asia, is safe, the officials said. "There is no damage to the dam," said Prabhakar.

Police and administrative officials are supervising the rescue operation in the tunnel. Bulldozers and cranes have been pressed to cut the boulders inside the tunnel so as to reach the trapped people.