A video circulated on social media Tuesday depicts rebel fighters beheading a boy after capturing him north of Syria’s second city Aleppo, a monitor said.
In an earlier clip, the boy was sitting in the back of the truck with fighters around him accusing him of being a member of the Al-Quds Brigades, a Palestinian group fighting with the regime forces.
However, Al-Quds Brigades denied that he was one of its fighters.
The second video shows the boy lying in the back of a truck as a fighter begins to cut off his head with a small knife.
The Britain-based Syrian Observatory for Human Rights confirmed that the video depicts rebel fighters.
Activists accused the Nurredin Zinki rebel group of carrying out the killing, but the group issued a statement condemning a “violation” and calling it “an individual mistake, that does not represent the general policy of the group.”
The US State Department said it could reconsider support for the group if the video was verified.
“If we can prove that this was indeed what happened and this group [Nurredin Zinki] was involved in it, I think it would certainly give us pause… and we’ll look at, frankly, any affiliation or cooperation with this group we may have going forward, if these allegations are proven true,” spokesman Mark Toner said Tuesday.
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.
According to Syrian Observatory for Human Rights head Rami Abdel Rahman, “the boy is no more than 13 years old, he was captured Tuesday in Handarat area, but the incident took place in a rebel held area in Aleppo city, Al Mashhad neighborhood to be exact.”
He could not confirm if the boy was a Palestinian or a child soldier.
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.