A three-year-old girl was allegedly raped, murdered and her face mutilated beyond recognition by a teenager who was caught after he dumped her body at an isolated place in a west Delhi neighbourhood, police said on Friday.

The incident occured on Thursday evening when her parents, who both work as construction labourers, reported her missing from her home.

A senior police officer told media that the accused, 16, offered the girl, living with her parents in Rohini's Narela area, some sweets when she was playing outside her home.

He then took her to a public lavatory where he allegedly raped her and then killed her at a nearby isolated place, the police officer said.

"The minor's throat was strangulated when she cried of pain. The accused even defaced her face with some hard substance, possibly a stone, to conceal her identity," the officer said. The minor's body was sent for an autopsy and doctors have confirmed the sexual assault.

The boy then dug a trench near the murder spot and dumped the body into it. As he was closing the pit, some locals got suspicious seeing the boy's clothes with blood stains all over and collecting earth at the spot, said the officer. 

They checked the pit and found the minor lying dead inside, he said, adding the boy was caught and handed over to police.

A case has been registered a rape and murder case under the Indian Penal Code and the Protection of Children from Sexual Offences Act.

But the accused being under 18 is unlikely to be tried as an adult.

He has been brought before a juvenile justice board and sent to a children's correction home.