Dozens of foreign-backed insurgents were killed and several others severely injured in violent clashes between rival terrorist groups in Syria. Al-Qaeda-linked al-Nusra Front insurgents killed on Friday at least 50 rival insurgents from the so-called Islamic State of Iraq and the Levant (ISIL) in the Eastern Deir Ezzur Governorate near the border with Iraq, Al-Alam reported. Reports say the al-Nusra Front has taken control of the Shoula district and is advancing in other areas of the province. The surge in infighting highlights the divisions between militants making unrest in the war-torn country. Rival militant groups have been lately engaged in fierce fighting. The infighting has escalated in the past months, amid gains by the Syrian army across the country. In recent months, the Syrian army has managed to liberate a number of cities and towns from militant control. Clashes between the militant groups still continue despite a recent order by Al-Qaeda leader Ayman al-Zawahiri to stop the infighting. Months of violent conflicts among different terrorist groups have killed thousands of Takfiri militants in Syria. Also on Friday, foreign-backed militants reportedly shelled an election rally in Southern Syria, killing at least 22 people. The (so-called) Syrian Observatory for Human Rights, which is based in London, said the attack hit a tent where supporters of President Bashar al-Assad had gathered in the city of Dara’a. The June 3 poll will be held only in government-controlled areas. Syria has been gripped by a foreign-hatched insurgency war since 2011. According to reports, western powers and their regional allies - especially Qatar, Saudi Arabia and Turkey - are supporting the militants operating inside Syria. ?