The operation to rescue 40 construction workers, who were trapped in debris following a tunnel collapse in Uttarakhand's Uttarkashi district, entered the fifth day on Thursday, media reports said.

The workers are trapped in the debris for at least 96 hours now.

The trapped workers have been provided food and medicines. The rescue teams are maintaining regular communication with the workers.

The tunnel on the Brahmakal-Yamunotri National Highway in Uttarakhand's Uttarkashi collapsed in the wee hours on Sunday.

The National Disaster Response Force (NDRF), State Disaster Relief Force (SDRF) and police are conducting the rescue operations.

A narrow opening was earlier made to insert an oxygen pipe in the tunnel and help the trapped labourers.

No casualties have been reported so far.