At least 45 whales have died in the southern Indian state of Tamil Nadu after more than 100 of the animals were stranded on the shore at Tuticorin.

The whales were spotted along a stretch of beach on Monday evening.

Locals together with teachers and students of a local college tried to float the whales back out to sea, but they kept returning to the shore.

The last time such an incident occurred in Tuticorin, was in 1973 when 147 whales died.

"At least 45 whales are dead and about 36 others which were rescued and pushed back into the sea are still in the vicinity of the shore,'' Dr Patterson Edward, director of the Tuticorin-based Sugandhi Devadasan Marine Research Institute, told BBC Hindi's Imran Qureshi.

Whale expert Kumaran Sathasivam said it is "very difficult" to rescue stranded whales because they all need to be pushed into the sea at the same time.

"Otherwise, they will return to be with the whale that is in distress. The whales emanate a sound that is not audible to human beings and that makes them return to the shore," he said.

"Also, because of their weight they are not able to get back into the water and their bodies gets overheated, and they die on the shore. You need to constantly pour water on them because their bodies are covered in a layer of fat."

He said it was hard to know if the whales that had been pushed back would survive because there was a strong possibility that they would be too exhausted to swim out to sea.