Algerian aviation authorities have lost contact with an Air Algerie plane flying over the Sahara.
More than 100 people are said to have been on board, nearly half of them French.
Air traffic control says communication was lost 50 minutes into the five-hour flight. The plane is thought to have been flying over Mali, but there is some confusion concerning events.
Flight AH 5017 was en route overnight from Ouagadougou in Burkina Faso to Algiers.
110 passengers and six crew were on board, according to the Spanish airline Swiftair, which owns the plane.
The airline’s representative in Burkina Faso said the passenger list included 50 French citizens. Earlier, France’s transport minister had said it was likely that there were many French people on board.
In France crisis centres have been set up at Paris’ Charles de Gaulle airport and in Marseille.
Swiftair said in a statement that the plane was supposed to land in Algiers early this morning but never reached its destination.
The pilot made a request to change route because of a storm, according to
Burkina Faso’s transport minister, but other reports speak of contact being made much later during the flight.
A diplomat in Mali has said the north of the country was struck by a powerful sandstorm overnight.