Algeria's national airline, Air Algerie, says it has lost contact with one of its planes flying from Burkina Faso.
Contact was lost about 50 minutes after take-off from Ouagadougou, the airline is quoted by Algeria's state news agency as saying.
The passenger airliner, last seen at 0155 GMT, was bound for the Algerian capital Algiers, it added.
Flight AH 5017 had 110 passengers and six crew on board, officials said.
"In keeping with procedures, Air Algerie has launched its emergency plan," Air Algerie officials, quoted by APS news agency, said.
The plane is chartered from Spanish airline Swiftair.
In a statement (in Spanish), Swiftair said that the aircraft was an MD83 and that they were unable to establish contact with the plane. The plane was originally scheduled to land at 0510 local time, it said.
Flight AH 5017 flies the Ouagadougou-Algiers route four times a week, AFP news agency reported.