The NAF 466 aircraft disappeared on 12 September with two pilots on-board after taking-off for a routine operational flight from the Yola Air Force Base.
The Nigerian Defence Headquarters (DHQ) said in a statement that the aircraft was expected back by midday the same day, but all efforts to establish contact with the jet did not yield results.
"Search-and-rescue effort is ongoing to establish contact with the crew," DHQ said.
Local farmers in the Gombi area have claimed to have seen a low-flying aircraft near the mountainous village of Gabun three days ago and might have crashed, This Day reported.
A witness named Adamu Bello said: "I’ve never seen a jet flying so low over our mountains before. I could even make out the doors of the plane clearly.
However, an unnamed DHQ source told the publication that the farmers might have seen another NAF aircraft searching for the missing jet.
The NAF pilots searched the Gombi local government area, but did not find the wreckage of an aircraft, the source added.
The aircraft had recently participated in an aerial bombing mission against the Boko Haram militants, who have captured territory in Adamawa, Borno, and Yobe states in the past two weeks.
It is unclear if the missing plane had crashed accidentally or was shot down by terrorists, local media reported.
Manufactured by Germany’s Dornier and French Dassault-Breguet, the Alpha Jet is a trainer/ light attack aircraft, and is currently being operated by Nigeria, Cameroon, Ivory Coast and Togo.
Image: A Nigerian Air Force Dassault-Dornier Alpha Jet went missing around Adamawa State on 12 September. Photo: courtesy of Kenneth Iwelumo.