INDIAN police have arrested a 20-year-old man for allegedly raping a 100-year-old grandmother at her home.

The alleged assault - on Tuesday, October 23 - took place while the victim was alone at home in Chakulia village, Nadia, West Bengal, according to police.

Police arrested Argha Biswas, 20, shortly after the alleged sexual assault after family members found the suspect.

The 100-year-old's granddaughter who does not wish to be named, said: "I heard some strange noises but when I looked through the window, I I immediately called others to help when I saw my grandmother."

The Indian police immediately arrested the suspect, after a initial court hearing he is now in 14 days’ judicial custody before another hearing takes place.

According to local reports, Biswas told reporters outside the court that he was "under the influence of alcohol and did not know what I was doing".

The centurion was taken to a hospital following the alleged incident but was discharged yesterday,

Rupesh Kumar, a senior police officer, said: "She was sleeping alone in her home. The house wasn't locked as the village culture.

"Her family members found the man when she cried for help.

"When we arrived, we found Argha Biswas under the bed, he was caught by the family members of the old woman."