The video, circulated on social media on Tuesday, shows the boy laying in the back of a truck when a fighter begins to cut off his head with a small knife.
One fighter shouts "we will leave no one in Handarat", which is north of Aleppo city where there has been fighting between rebels and regime forces.
Also Read
In an earlier clip, the boy was sitting in the back of the truck with fighters around him accusing him with being a member of Al Quds brigade, a Palestinian group fighting with the regime forces.
Earlier in July, Amnesty International issued a report saying that Islamist rebels and jihadists in Syria are guilty of war crimes, accusing them of "a chilling wave of abductions, torture and summary killings".
The London-based rights group named five Syrian anti-regime factions operating in northern Syria among them Nureddin Zinki.
Activists accused Nurredin Zinki group of carrying out the killing, but the group issued a statement condemning a "violation" that was "an individual mistake, that does not represent the general policy of the group".
According to Rami Abdel Rahman, Syrian Observatory for Human Rights chief, "the boy is no more than 13 years old, he was captured yesterday in Handarat area, but the incident took place in a rebel held area in Aleppo city, Al Mashhad neighbourhood to be exact".
He could not confirm if the boy was a Palestinian or a child soldier, though he said Al Quds brigade denied that he was one of its fighters.
Nureddin Zinki added that "the persons who carried out this violation were arrested and handed over" to a judicial committee for investigation.
Syria's conflict began in 2011 with the repression of anti-government demonstrations and has evolved into a multi-front war that has left more than 280,000 dead and forced millions from their homes.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app