"We had given a tip off to the Nepalese authorities about the doctor's possible whereabouts," Haryana police Commissioner (Gurgaon) Mohinder Lal said over phone in Chandigarh.

The Haryana police and the CBI are in touch with the Interpol and the Nepalese authorities in connection with the case.

"CBI is preparing for the doctor's extradition at the earliest," he said adding once the extradition process was over both the CBI and Haryana police teams will leave for Nepal to bring the doctor to India.

"Nepal is a sovereign country so Indian police cannot do any activity there independently," he said.

Lal said Haryana police was keeping a track of the doctor and had given specific information about his possible hideout in Nepal to the authorities of that country about three days back.

"We had handed over the description and other details of the wanted doctor and also issued Red Corner notice for him," he said adding Haryana police is constantly in touch with the Nepalese authorities.

Asked how much time it would take for the extradition, Lal said "it will be over very soon. Very soon we will bring the doctor back to India through Interpol".

Dr Kumar, 40, is believed to have conducted over 500 illegal kidney transplant operations.

Haryana police is still raiding possible hideouts of two other doctors at various places in the state in connection with the racket.

Meanwhile, UP DGP Vikram Singh said that "there has been some exchange of vital information through official channels" between Nepal and India.

"Whatever needs to be done will be done and there is a set procedure for doing such things," he added.

Additional DG (Law and Order) of UP Police Brij Lal said Nepal police has started interrogating Kumar after he was brought to Kathmandu following his arrest in a forest resort in Nepal's Chitwan district yesterday.

Meanwhile, Moradabad Senior Superintendent of Police Prem Prakash said co-accused in the kidney racket Dr K K Agarwal and Jagdish, driver of another accused Dr Upendra, who are on police remand since Wednesday, are still being interrogated.

"But their interrogation is yet to throw up any vital clues", he said.