The Syrian plane took off from Damascus airport, approx at a time when it was announced that the capital had been captured by the rebels, according to data from the website Flightradar, it suggests that the deposed president Bashar al-Assad may have been on that plane, writes Reuters.
The media added that the plane initially flew towards Syria's coastal region, a stronghold of Assad's Alawite sect, but then made a U-turn and flew in the opposite direction for several minutes before disappearing from radar.
Reuters could not determine who was on the plane.
Two Syrian sources said it was very likely that Assad possibly killed in a plane crash, and that it is a mystery why the plane made a sudden turn and disappeared from the map.
"It disappeared from the radar, it's possible that the transponder was turned off, but I believe it's more likely that the plane was shot down..." a Syrian source said without elaborating.
As the rebel advance has strengthened over the past week, there has been speculation that Assad may seek refuge in Moscow or his other main ally, Iran.