By Stacy Meichtry and Drew Hinshaw 

An Air Algérie jetliner with 118 people on board lost contact with ground controllers on Thursday and likely crashed in northern Mali, the airline and French officials said, marking the latest in a string of airline incidents around the world that have mobilized aviation regulators and safety officials.

For the second time in a week, executives and air-safety regulators struggled to ascertain what happened. The jetliner, a Boeing Co. MD-83, took off from Burkina Faso en route to the Algerian capital, Algiers. If a crash is confirmed, authorities would then also have to grapple with the daunting task of retrieving wreckage and human remains from a desolate and tense conflict zone.

The fate of Air Algérie Flight 5017--which lost contact at 1:55 a.m. local time, 50 minutes after departing from Ouagadougou, Burkina Faso--reverberated far beyond the Sahara, from where it was last heard. Fifty-one passengers on board were French nationals, many of them due to catch connecting flights in Algiers to return home to France.

French President François Hollande summoned senior members of his cabinet for a crisis meeting Thursday, deploying fighter jets and other military forces in the region to search for wreckage over northern Mali--a Texas-size area where authorities believe the plane went down.

By nightfall, France was plunged into a state of national mourning. Friends and family members of the missing passengers gathered at airports across France, awaiting updates, as Mr. Hollande told the country that "no trace" of the plane had turned up.

"The search will last as long as necessary," he said. "This is a moment of gravity and of pain."

The plane was also carrying 24 passengers from Burkina Faso, eight Lebanese, six Algerians, five Canadians and four Germans. The passenger list also included people from Luxembourg, Mali, Belgium, Niger, Cameroon, Egypt, Ukraine, Romania and Switzerland. The nationality of three passengers was still being verified.

All six crew members aboard the plane are from Spain. The plane was operated by Swiftair SA, a Spanish charter company.

The plane's exact flight path isn't clear. But authorities lost contact while it was over northern Mali--the site of a simmering Islamist insurgency. Air Algérie SpA said it had ordered the plane to change course because of bad weather. Before losing contact, the plane had changed its flight path because of "particularly difficult weather conditions," Mr. Hollande said.

Still, the overflight of Mali is likely to fuel questions by airline executives and regulators over whether commercial jetliners should fly over conflict zones. Last week's downing of Malaysia Airlines Flight 17 over war-torn eastern Ukraine had ratcheted up that debate.

It also follows a temporary flight ban imposed by the U.S. Federal Aviation Administration on American carriers using Tel Aviv's airport, after a Hamas-fired rocket landed nearby this week. The ban was lifted late Wednesday.

And in March, another Malaysia Airlines flight vanished, a mystery that still hasn't been solved.

French officials on Thursday said there were no signs the Air Algérie flight was shot down, but they aren't ruling out the possibility. The FAA has warned airlines to be extra vigilant when flying over Mali and has gone as far as to ban U.S. carriers from flying over the African country at lower altitudes, citing "insurgent activity, " including the threat of antiaircraft missiles, rocket-propelled grenades and rockets.

Commercial jetliners flying in Africa have traditionally had the worst accident record. In the past five years, African carriers accounted for 23% of fatal aircraft accidents in the years spanning 2009 to 2013, even though the region sees far less flying than others. The region last year suffered 7.45 crashes per one million flights. That is down significantly from its five-year average of 13.53 crashes per million flights, though still far behind the global average of 2.51 crashes over the same five-year period, the International Air Transport Association said this year.

If the jet went down in northern Mali, accessing the site would be a challenge. Since its medieval heyday as a thoroughfare for caravans traveling on camelback, northern Mali has been rendered barren by centuries of desertification that have left it a remote stretch, strewed with rocks and dunes.

That landscape is likely to hinder the search effort. Towns and military outposts are separated by hundreds of miles and the occasional nomadic tent camp. Massive sandstorms swirl up quickly, including one on Thursday.

The site also sits in the midst of a civil war. For days, Malian media have reported small desert battles among a group of jihadists looking to impose Islamic law, a second militia that wants autonomy for the local Tuareg people, a third group that seeks to defend the interests of the resident Arab population, as well as Mali's weak military.

Armed convoys drive through frequently, trafficking weapons, cigarettes, and, some Western officials suspect, cocaine. In 2012, the area was conquered by a group of al Qaeda allies.

Last year, France dispatched thousands of troops to the area to chase terrorists, even scanning the desert with hand-held metal detectors to find buried weapons. Still, Malian and French officials acknowledge the area remains infiltrated by al Qaeda-inspired jihadists; kidnapping of foreigners poses a distinct threat.

Inti Landauro, Benoît Faucon, Robert Wall and Christopher Bjork contributed to this article.

Corrections & Amplifications

Earlier we incorrectly said that Air Algérie said Flight 5017 crashed. The airline said it "likely" crashed.

Write to Stacy Meichtry at stacy.meichtry@wsj.com and Drew Hinshaw at drew.hinshaw@wsj.com

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