Chances of two-year-old boy look bleak four days after falling into abandoned bore well in Tamil Nadu’s Trichy district.

Rescue workers have been carrying out a major operation to save a two-year-old boy stuck in a narrow well in south India for four days but chances of his survival look bleak, according to officials.

The toddler, Sujith Wilson, fell into the abandoned bore-well while playing with his friends near his home in Tamil Nadu state’s Trichy district on Thursday evening.

He was initially stuck at about 10 metres (33 feet) but had fallen further to over 25 metres (82 feet), National Disaster Response Force regional head Rekha Nambiar said by phone on Monday.

“As initial attempts to bring him out by a rope failed, our teams are drilling a one-metre wide tunnel parallel to the well since Saturday to reach the boy,” Nambiar said.

“The progress is slow because we have to drill through 30 feet (9.1 metres) of sheer rock after which we get regular loose soil and try and reach him via a horizontal passage. The operation could take 12 hours or more,” she said.

There were conflicting reports of the depth of the well, with estimates saying it is between 180 and 300 metres (591 and 984 feet).

Officials expressed concern as Sujith has been trapped in the bore-well without food and water.

“Unfortunately since he slipped, he is engulfed by mud. Only his palm and fingers can be seen with the help of the camera. We just hope he has found an air pocket … the situation is grim but we are trying our best,” Nambiar said.

Oxygen was being supplied but he had stopped responding to calls, local media reported, adding prayers were also being held in temples, mosques and churches in the state.