Days of torrential monsoon rains have battered the southern coastal state of Kerala, with blocked roads into the Wayanad district disaster area complicating relief efforts since Tuesday.

The number of fatal floods and landslides in India has increased in recent years and experts say climate change is exacerbating the problem.

Army teams were working around the clock to build a temporary bridge over raging waters to help search efforts after earlier relying on jury-rigged ziplines to transport bodies that had been recovered.

Saraswathy, one of hundreds of labourers on the tea estates struck by a wall of mud before dawn on Tuesday, said she had been unable to contact her sister and niece in the days since.

"After this many days, we've lost hope," Saraswathy, who goes by one name, told AFP.

"I came back from the hospital, I kept looking for their bodies but couldn't find them," she said. "Eventually I couldn't stand it. Seeing all these bodies, I almost fainted."

Wayanad is famed for the tea estates that crisscross its hilly countryside and which rely on a large pool of labourers for planting and harvest.

Brick-walled row homes built to accommodate seasonal workers were inundated by a powerful wall of brown sludge as labourers and their families slept.

The bodies of at least 176 people had been recovered from the disaster site by Thursday, the office of Kerala revenue minister K. Rajan said.

But the final toll is certain to rise, with rescuers reporting the gruesome discovery of dozens of body parts recovered from flood waters or found buried in the muddy earth.