Four employers were also arrested in this connection.
The raids were carried out jointly by police and the Labour Department after a complaint by NGO Bachpan Bachao Andolan (BBA).
The children had been staying in Delhi for the past 4 to 6 months and were paid as low as Rs 200 per month. Some of the boys reported that the employer had made an advance payment of Rs 5,000 to their parents before bringing them to Delhi, a statement issued by the BBA said.
These children said that they were often not allowed to speak to their kin without the permission of employer.
Marks of rashes and wounds on their body, especially on hands, symbolised the conditions under which they were forced to live and work.
"I don't remember how my parents look. The only person I know or recognise is my employer," a seven-year-old child said, who broke down when questioned whether he would like to go back to his mother.