The aircraft was on a routine training mission but lost radar and radio contact around 60 km north of Tezpur.
According to PTI, the plane went missing at 11:30 am, around 60 km north of the Tezpur IAF base from where it had taken off.
Defence public relations officer (Guwahati/Shillong), Lt. Col. Suneet Newton told PTI that the aircraft had lost radar and radio contact with the airbase.
Sonitpur district Deputy Commissioner Manoj Kumar Deka told reporters in Tezpur that the Air Force base had informed him that the Su-30 plane with two pilots had taken off from the airbase at 10.30 am for a regular sortie and lost contact with the IAF air traffic control over Dubia in nearby Gohpur.
Tezpur Air force station is located 172 km from the China border.
The Air Force, after carrying out a search on its network, informed the deputy commissioner about the incident.
The DC said he then immediately alerted the neighbouring district administrations about the missing plane.