Syrian officials could not immediately be reached for comment. The Syrian Observatory for Human Rights, a British-based monitoring group, said a nearby town and a village had fallen to the rebels in addition to the base, Liwa 52.

The southern region near the border with Jordan and Israel is one of the areas where insurgents have inflicted significant defeats on Assad in the last three months, notably by capturing the Nasib border crossing with Jordan on April 1.

Less than 100-km (60 miles) south of Damascus, the area is one of the last major footholds of rebel groups that are not dominated by hardline jihadists such as Islamic State and the Nusra Front, al Qaeda's Syrian arm, although Nusra also has a presence there.

Latest News from World News Desk