Hollande held a meeting following the disappearance of the Air Algeria at 5 p.m. on Thursday at the Elysee. The meeting was attended by Prime Minister Manuel Valls, Minister of Foreign Affairs and International Development Laurent Fabius, Minister of Defence Jean-Yves Le Drian, Minister of the Interior Bernard Cazeneuve, and Minister for Transport Frederic Cuvillier, Xinhua reported.
"We cannot identify the causes of what happened. (But), everything must be done to find this plane. The search will take as long as needed," Hollande told reporters after the crisis meeting on the missing plane carrying 51 French passengers.
"Following particularly difficult weather conditions", the plane's crew was said to have changed the flight's path from the intended direction, the French president said confirming previous reports.
He vowed to use all the military means in Mali to find the aircraft, and cancelled a planned visit to overseas territories scheduled for Thursday because of "a moment of gravity and sorrow".
Earlier, Fabius said two French Mirage warplanes have been dispatched around the northern Malian city of Gao to try find the plane reported missing 50 minutes after taking off from Burkina Faso to Algiers.
Operated by Air Algerie, the Spanish MD-83 aircraft carried more than 110 passengers and six Spanish crew members.
Citing a judicial source, the news channel BFMTV said Paris prosecutor opened a preliminary investigation for "involuntary homicide" following the eventual crash of the aircraft.