So far police have arrested 10 people in connection with the organ harvesting scam and expect to arrest more in the coming days as they interrogate mastermind Raju Ramakant Rao, police say.
Rao is now in the custody of the Delhi police.
The gang has been operating for the last one-and-a-half years in Delhi and Kolkata, he said.
Rao is also suspected to have been involved in a similar racket in two other Indian cities, police said.
Late last week
, Delhi police
arrested five people, including two surgeons' assistants, in connection with the illegal trafficking ring.
Police allege that the suspects lured poor people to give up their kidneys for a small fee, while they sold the organs at a huge mark-up on the black market.
The kidney donors were recruited from all over India, including the provinces of West Bengal, Kanpur, Delhi and Chennai. They were then brought to a private hospital in Delhi for the procedures, according to the police.
The scam also involved falsified documents given to poor patients by a gang at the city's Indraprastha Apollo Hospital Delhi, according to Mandeep Randhawa, Deputy Commissioner of Police of Southeast Delhi.
Police are also investigating transplant committee members at the hospital, as all institutions in India are required to have a committee approve kidney transplants, according to R. P. Upadhyaya, the joint commissioner of Delhi Police.
Those committees are legally required to consist of health ministry officials, hospital officials and doctors.
The police said they are monitoring other Delhi hospitals.
Randhawa told CNN that Delhi police had known of five cases where a kidney has been sold over a period of four to five months.
"We are checking documents and trying to contact recipients," he said.
The group have been working over a period of four to five months, he added.
"We don't know how much money has been exchanged -- we are trying to track down the recipients and going through documents to uncover this," said Randhawa.
Hospital denies involvement
The parent company of the hospital, Apollo Hospitals Group, denies any wrongdoing and, in a press release, said that it ensures "all due process as per the law" is adhered to in its organ transplant process. It said the hospital is cooperating fully with police in their investigation.
"We are cooperating and providing to them all information required to help them in their investigation," the statement reads. "This matter is of grave concern and our teams are extending all support to the police."
Forged documents, the hospital insists, were used to circumvent its stringent procedures.
"The hospital has been a victim of a well-orchestrated operation to cheat patients and the hospital."