The plane dropped off the radar Wednesday while flying over the Andaman Sea between the southern city of Myeik and Yagon. A search and rescue operation is now underway.
"Communication was lost suddenly at about 1:35pm when [the plane] reached about 20 miles west of Dawei town," read the army chief’s statement.
Initial reports of the number of passengers on board ranged from 116 to 105. However, the latest count from military and civil aviation officials put the figure at 120, according to Reuters.
Three military planes and six navy ships are continuing to search for the Chinese-built Shaanxi Y-8 transport plane.
"We don't know what exactly happened to this plane after the loss of contact," Kyaw Kyaw Htey, a civil aviation official at Myeik airport, told Reuters.
Meanwhile, an airport source told AFP: “We think it was a technical failure. Weather is fine there."