An Iranian military aircraft crashed into a mountain range in the northwest of the country, state media reported.
The official IRNA news agency reported that the Russian-made MiG-29 aircraft crashed in Ardabil Province at around 09:00 local time on December 25.
Amateur video footage published on the social media accounts of various media outlets in Iran appeared to show smoke rising above snow-capped peaks.
The semiofficial Fars news agency reported that the plane had been found but there was no trace of its pilot and that he could have ejected from the aircraft.
A search and rescue operation was launched for the pilot, who was identified as Colonel Mohammadreza Rahmani.
"Following the crash of a military plane in Ardabil, helicopter and rescue groups have been sent to the region," Iran's Red Crescent said in a statement on its website.
The official website of the army said search and rescue efforts had been hampered by bad weather, with snow making areas impassable.
There have been no reports of casualties in the incident or the number of people onboard.
The fighter jet was test flying the recently overhauled plane and had taken off from the Tabriz air base earlier in the day.
Iran’s air force has an assortment of U.S.-made military aircraft -- purchased before the 1979 Islamic Revolution -- as well as Russian-made MiG and Sukhoi planes.
Decades of Western sanctions have made it hard for Iran to maintain its aging fleet.
Iranian Military Aircraft Crashes Into Mountain Range