He said 500-700 Islamic State fighters are currently active in the towns of Jamlah and Ash-Shajarah, adjacent to the Israeli border in the southern Golan Heights.
No ammunition or weaponry has reached the Free Syrian Army on the southern front in three months, he added.
Salaries have also been cut, he noted. Islamist Nusra Front combatants earn $300 a month and the salary of IS fighters can reach $500, while the average FSA combatant earns just $70 a month.
“If the donor states do not take a firm stand, within two months most fighters in the southern front will switch to Nusra or ISIS,” he said.