Angry parents have protested outside a private school in India's northern Gurugram city over the murder of a seven-year-old pupil.

The boy was found with his throat slit inside a toilet of the Ryan International School in Gurugram, a financial and technical hub, located in the southern suburbs of the capital, New Delhi.

A bus conductor, named only as Ashok, was arrested late on Friday night after investigations, Gurugram deputy commissioner of police Simranjit Singh told reporters.

The man had attempted to sexually assault the boy and attacked him with a knife when the child tried to raise an alarm, Singh said.

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Acting principal Nirja Batra was suspended, but agitated parents protested outside the school and at various locations in Gurugram on Saturday demanding further action against education authorities.

They said the crime took place on school premises and accountability needed to be addressed for the lack of security for their children.

"The school could not ensure basic safety for my son. I want action against the school administration," Varun Thakur, the child's father, said.

Singh said local authorities would conduct a separate investigation on lapses by the school, following which action would be taken.

Hundreds of parents had barged into the school building on Friday, flung furniture around and broke windows and glass award cases.

A total of 10,854 cases of child rape were reported in India in 2015.

Activists say that many more cases likely went unreported. In most cases, the perpetrator knows the victim.