Flight missing with 116 on board
The official Algerian news agency said air navigation services lost track of the Swiftair plane 50 minutes after take-off in the early hours of Thursday.
Swiftair, the private Spanish airline, confirmed 116 people were on board.
The flight path of Flight AH5017 from Ouagadougou, the capital of the west African nation of Burkina Faso, to Algiers was not immediately clear.
Ouagadougou is almost directly south of Algiers, passing over Mali where unrest continues in the north.
A senior French official said it was unlikely that fighters in Mali had weaponry that could shoot down a plane.
The official, who spoke on condition of anonymity, said the fighters have shoulder-fired weapons which could not hit an aircraft at cruising altitude.