Algiers (AFP) - An Air Algerie plane missing since early Thursday over Mali with 116 passengers and crew, including 50 French nationals, on board probably crashed, French President Francois Hollande said.
Speaking on French television, Hollande said: "Everything leads us to believe that the plane has crashed."
He said the plane's Spanish crew had signalled they were altering course "due to particularly difficult weather conditions".
He vowed to deploy all of France's military means in Mali, where it has hundreds of troops, to track down the wreckage of the missing plane.
Flight AH5017, which originated in Ouagadougou and was bound for Algiers, went missing in the early morning amid reports of heavy storms, company sources and officials said.
"Contact was lost with the McDonnell Douglas 83 at 1:47, a little after the pilots said they were diverting from the route due to meteorological reasons," Fabius said.
Algerian Prime Minister Abdelmalek Sellal was earlier cited as saying by Algerian radio that the plane dropped off the radar at Gao, 500 kilometres (300 miles) from the Algerian border.
The airline said it had 50 French, 24 Burkinabe, eight Lebanese, six Algerians, six Spanish, five Canadians, four Germans and two Luxembourg nationals on board.
Aviation sources told AFP the MD-83 was leased from Spanish company Swiftair.
Its six-member crew were all Spanish, said Spain's airline pilots' union Sepla, and Swiftair confirmed the aircraft went missing less than an hour after takeoff.
- Poor visibility -
Air Algerie said the passenger manifest also included one person each from Belgium, Cameroon, Egypt, Mali, Nigeria, Romania, Switzerland and Ukraine as well as "three nationalities yet to be determined".
The plane had apparently been given the "all clear" following an inspection in France only this week, the French civil aviation authority DGAC said.
In France, two emergency cells had been set up, at the DGAC and at the foreign ministry, DGAC said, in addition to another two at Roissy-Charles-de-Gaulle airport in Paris and at Marseille airport.
DGAC said that many passengers had been due to catch onward connecting flights to Paris and Marseille.
Contact between air traffic control and the aircraft was lost over restive northern Mali as it flew towards the border with Algeria, a source within the airline told AFP, speaking on condition of anonymity.
In Mali, the prime minister's office also said contact was lost around Gao.
"The plane was not far from the Algerian frontier when the crew was asked to make a detour because of poor visibility and to prevent the risk of collision with another aircraft on the Algiers-Bamako route," an airline source said.
"Contact was lost after the change of course."
A controller in Mali, also speaking on condition of anonymity, said the area was rocked by "strong storms" overnight.
- 'Emergency plan' -
Two French Mirage 2000 warplanes based in the Chadian capital N'Djamena were taking part in the search for the plane, the French military said.
Air Algerie, in a statement carried by national news agency APS, said it had initiated an "emergency plan" in the search for AH5017, which flies the four-hour passenger route four times a week.
"Air traffic control had their last contact with AH5017 on the Ouagadougou-Algiers route today, July 24, at 0155 GMT, 50 minutes after takeoff," an airline statement said.
The search for the missing flight comes less than six months after one of Algeria's worst air disasters.
In February, a C-130 military aircraft carrying 78 people crashed in poor weather in the mountainous northeast, killing more than 70 people.
The plane had been flying from the desert garrison town of Tamanrasset in Algeria's deep south to Constantine, 320 kilometres (200 miles) east of Algiers.
Tamanrasset was the site of the country's worst-ever civilian air disaster, in March 2003.
In that accident, all but one of the 103 people on board were killed when an Air Algerie Boeing 737-200 crashed on takeoff after one of its engines caught fire.
The sole survivor, a young Algerian soldier, was critically injured.