BEIRUT A video published on Thursday showed fighters of the al Qaeda-linked Nusra Front in Syria executing 11 men they accused of taking part in massacres by President Bashar al-Assad's forces.
The film is believed to be from eastern Deir al-Zor province and dates from some time in 2012, according to the Syrian Observatory for Human Rights, an opposition monitoring group.
The Observatory's head, Rami Abdelrahman, said the Nusra Front has recently been releasing several videos of their past operations. He said the man seen executing the prisoners in the video - a Nusra commander - had been killed in March 2013 in battles with local tribes in the province.
The footage shows the commander, his face covered in a black balaclava, shooting each prisoner in the back of the head as they kneeled, blindfolded and lined up in a row in the sand.
"The sharia court for the eastern region in Deir al-Zor has sentenced to death these apostate soldiers that committed massacres against our brothers and families in Syria," the executioner said on the video.
Islamist militants with black flags shouted "God is great" as each man was shot. The executioner returned to some victims, firing more bullets into them to make sure they were dead.
Videos of executions and torture have become increasingly common in Syria, where more than 94,000 people have been killed in a conflict now in its third year, according to the British-based Observatory, which has a network of activists in Syria.
Such videos posted online are hard to verify due to government restrictions on access for independent media.
The Nusra video is the second video to be published in the past two days showing executions by fighters who say they are from al Qaeda-linked groups.
A video issued on Wednesday from the northern province of Raqqa, which is controlled by Islamist rebels, showed three blindfolded men sitting on the curb of a central roundabout before being shot in the head with a pistol.
A man speaking in the video said the executions were revenge for killings in the coastal town of Banias two weeks ago. Photos and videos of the alleged Banias massacre showed dozens of mutilated bodies, many of them children, lying in the streets.