'Earlier, they used to buy empty blood bank wrappers from the CSMMU at a cost of Rs.100 per piece. A few months ago, they started getting the wrappers printed in a printing press in Basti district. Besides private hospitals, the name of some private blood banks has also come to light and more arrests are expected soon,' Chandra said.

He said the police had clues that some prominent private blood banks in the Aliganj, Vikasnagar, Mahanagar areas of the capital and around the CSMMU campus were also involved in the racket and their names would soon be made public.

The CSMMU vice-chancellor has admitted that the racket is going on since long.

'A few days ago, policemen on the CSMMU outpost nabbed two people who were trying to sell blood to a person on the campus. It is possible that some of the college staff are also involved in the racket,' CSMMU Vice-Chancellor Saroj Chooramani Gopal said.

Chandra said that according to information given by gang leader Deepak Pandey, there were over two dozen people involved in the illegal trade.

'While we managed to arrest six, eight others managed to escape. Efforts are on to nab them,' the police officer added.

Though there was no official confirmation, police sources said the six arrested men had confessed that on several occasions they had duped gullible customers by giving them pouches containing animal blood.

'We have sent the blood samples for testing. Let's see what the reports suggest,' Superintendent of Police (West) Paresh Pandey said.