The Israel Defense Forces declared the area around the Golan Heights' Quneitra crossing a closed military zone, in the wake of fighting in Syria.

IDF officials expressed concern that the fighting could spill over into Israel. The rebels in Syria have managed to take over the crossing for several hours in past. The crossing primarily serves United Nations forces.

In February Syrian state TV, citing a military official, said troops and pro-government gunmen had captured the areas of Rasm al-Hour and Rasm al-Sad, south of the town of Quneitra, back from the rebels.

On Sunday, activists said that an Al-Qaida splinter group had wrested control of key parts of the eastern Syrian province of Deir al-Zor from other rebel groups.

More than 100,000 civilians have fled the province following weeks of intense clashes between Islamist insurgents, the anti-Assad Syrian Observatory for Human Rights monitoring group said.

Civilians in Deir al-Zor lived through more than two years of fighting between opposition fighters and the government. Now they are dealing with a second wave of internecine war that has devastated parts of the country that the opposition considers "liberated" from Assad's forces.

The Islamic State in Iraq and the Levant (ISIL) - which started as an offshoot of Al-Qaida in Iraq but has since been disowned - took neighborhoods of Deir al-Zor city from the Nusra Front, Syria's official Al-Qaida affiliate, this weekend, according to the Observatory.

Some 230 militants have been killed over the past 10 days by the infighting, it added. Although ISIL made headway in the fight for Deir al-Zor, opposition groups rarely hold territory for long before clashes resume.