The "Islamic State of Iraq and Syria" (ISIS) will have been driven from all the territory it once controlled as a self-declared "caliphate" before the end of the year, French military chief Francois Lecointre said Thursday (September 6th).

The extremists, who conquered vast stretches of Iraq and Syria in 2014, have lost all but a pocket of land in Syria's eastern Deir Ezzor province between the Euphrates river and Iraqi border, though they remain present in the Syrian desert.

Lecointre predicted "the end of the physical caliphate of ISIS before the end of the year, probably late autumn", AFP reported.

France is part of the international coalition that has been fighting ISIS since 2014 and is now supporting Kurdish and Arab fighters of the Syrian Democratic Forces (SDF) as they battle to oust the extremists from their last holdout.

"Once the physical caliphate has fallen ... we will pose the question of how to reconfigure Operation Inherent Resolve," Lecointre said of the coalition.

Speaking to reporters, the general pledged to downscale the French troop contingent -- currently more than 1,000-strong -- "as soon as I can".