The police are looking for the baby's father, who is at large.
A daily wage earner allegedly sold his newborn daughter to a teacher in Dhupguri area in West Bengal's Jalpaiguri district for Rs 25,000 even as police has arrested a middleman, identified as Atul Basak, who helped in striking the deal.
Salma Begum, wife of a daily wage labourer Bulbul Haq, had delivered a baby girl at Moynaguri hospital on Saturday last, police said.
"On April 19, Salma was released from the hospital and she went back home. Once in Dhupguri, her husband struck a deal with a school teacher in Mathabhanga area identified as Partha Biswas, to sell off the baby in exchange of Rs 25,000," a senior police officer said.
"The deal was struck with the help of another school teacher of Netajipara primary school in Dhupguri, Atul Basak," the officer said.
"We have received a complaint from the mother and Atul Basak has been arrested. He is now being questioned for more details and a search is on to trace the whereabouts of Bulbul Haq, who is currently absconding," said Avaru Ravindranath, Superintendent of Police (SP), Jalpaiguri.
"We have informed about the case to Mathabhanga police station and have asked them to trace Biswas and the baby," the SP added.