Syria's war has killed just more than 312,000 people since it began in March 2011, over 90,000 of them civilians, the Syrian Observatory for Human Rights monitor said Tuesday (December 13th).

The group said it had recorded the deaths of 312,001 people since the war began, including nearly 16,000 children, AFP reported.

The toll includes more than 53,000 opposition fighters and nearly 110,000 pro-regime fighters, among them over 60,000 Syrian soldiers, but also tens of thousands of Syrian militiamen, members of Lebanon's Hizbullah and other foreign fighters.

The group said nearly 55,000 extremist fighters had also been killed in the fighting, most of them from the "Islamic State of Iraq and the Levant" (ISIL) or al-Nusra Front (ANF), now known as Fatah al-Sham Front.

The Observatory said it had also recorded the deaths of 3,683 people it had not been able to identify.

The UN Security Council is set to hold an emergency meeting on Tuesday to urgently address the crisis in Aleppo following reports that Syrian forces executed dozens of civilians in the city.

The UN said it had credible reports of pro-government forces in Aleppo executing dozens of civilians including women and children as the crucial battle for the city neared its end.