Extortionists have demanded Rs 10 lakh each from Dr B K Khetan and Dr Manoj Kumar Verma, assistant professors at the Nalanda Medical College and Hospital in Patna, the general secretary of the Indian Medical Association, Bihar chapter, Sahajanand Prasad Singh, said on Monday.

"We have requested Senior Superintendent of Police (Patna) N H Khan and other top authorities to provide the two doctors with security guards immediately and apprehend the extortionists," Singh said.

Dr Khetan, who is in the pathology department of the hospital, received the call at his Doctors' Colony residence in Kankerbagh on February 1. His colleague Verma of the ENT department received the call at his PC Colony residence in Kankerbagh on January 26.

The doctors have lodged complaints with the police.

Last year extortionists had killed surgeon A K Agarwal at his Kadamkuan nursing home following his refusal to pay money.