Cadaver dogs of Kerala police on Friday joined the rescue operation inside the partially collapsed Srisailam Left Bank Canal (SLBC) tunnel in Telangana in which eight persons remain trapped since February 22.
The team (including dogs and handlers) went inside the tunnel on Friday morning to locate the presence of humans, official sources said.
The cadaver dogs of the Belgian Malinois breed can detect smell even from a depth of 15 feet, they said.
After the dogs arrived by air from Kerala, the rescue officials went inside the tunnel on Thursday and prepared a plan on how and where to take the dogs to look for human presence.
The sources said 110 rescue personnel, including NDRF teams, also went inside the tunnel along with the equipment required for digging.
The cadaver dogs are specially trained to locate missing humans and human bodies.
The dogs were sent for the rescue operation following a request by the State Disaster Management Authority, whose help in the matter was sought by the National Disaster Management Authority, a Kerala government statement said on Thursday.
The rescue personnel had earlier used the services of a sniffer dog of the NDRF inside the tunnel for selecting the area to be taken up for digging to identify any human presence.
Eight persons -- engineers and labourers -- have been trapped in the SLBC project tunnel since February 22 and experts from the National Disaster Response Force, Indian Army, Navy and other agencies are making relentless efforts to pull them out to safety.
The rescue operation has been going on amid challenging conditions, including slush and seepage of water.