The accused was arrested by police on Thursday.
A girl in class IV was allegedly molested by a 24-year-old man inside the premises of her school in south west Delhi's Dwarka area, police said today.
The girl had gone to the school library on Tuesday along with two of her friends when the accused, identified as one Sachin, who works with a publishing house, allegedly molested her, police said.
Sachin was arrested today after the parents of some of the students staged a protest outside the school and alleged that the principal was unwilling to meet them to discuss the matter.
A case under the Protection of Children from Sexual Offences Act (POCSO) was registered this afternoon in connection with the alleged offence with Chhawla police station in south-west Delhi.
One of the parents, meanwhile, alleged that the accused had tried to molest all the three girls, although police said that inquiries so far suggest that only one of them was molested.
The parents also alleged that the victim's class teacher had asked the students not to mention the incident to anyone.
"Immediately after emerging from the library, the girls had gone to their class teacher and told them about the incident. But the teacher told them not to talk to strangers," the parents alleged.
Southwest district police said they were verifying the allegations.
"The accused has been arrested. He works for a publishing company and supplies books to the school," a senior police officer said.
Police will ask the school to provide footage of CCTV cameras on the campus to check if there have been other instances of similar assault on students. Further inquiries are on into the matter, police added.