IAF sources said the operation was continuing despite bad weather conditions in parts of Assam and neighbouring Arunachal Pradesh where the plane is suspected to have crashed.
The Sukhoi jet, with two pilots on board, went missing around an hour after taking off from the IAF base here at 10:30 AM.
A massive search operation, involving helicopter recce, was launched to trace the plane and the pilots.
The jet had lost radar and radio contact around 60 km north of the airbase, IAF had said yesterday.