Family members of Asif said that he was kidnapped on Wednesday from Rampur bazar where he had gone with his grandfather.
The kidnappers lifted him from the marketplace, Asif's father Abdur Rahim told the police in his complaint.
Asif's mother Jhuma Sarkar later received a phone call from the kidnappers demanding a ransom of Rs 15 lakh.
Parents of Asif later met Superintendent of Police Prasun Bandyopadhyay and told about frequent calls from the kidnappers demanding ransom, sources said.