BEIRUT • The Islamic State in Iraq and Syria (ISIS) on Saturday released a video showing 25 Syrian government soldiers being executed by teenagers in an ancient amphitheatre in the city of Palmyra.
The video documented an execution that reportedly happened shortly after the militant group captured the city on May 21.
It shows the soldiers in green and brown military uniforms being shot dead on the amphitheatre's stage, in front of an enormous version of the group's black-and-white flag.
The executioners, who all appear to be children or teenagers, are seen wearing desert camouflage and brown bandanas.
The killings are carried out in front of a relatively sparse crowd of men and children, who watch from the ancient theatre's seats. ISIS has reportedly carried out more than 200 executions, including of civilians, in and around Palmyra since it captured the city.
The executions in the Palmyra amphitheatre were first reported on May 27 by the Syrian Observatory for Human Rights, a Britain-based monitor, less than a week after ISIS captured the city.
At the time, Syria's antiquities director Mamoun Abdelkarim said he feared that the killings could signal the start of "the group's barbarism and savagery against the ancient monuments of Palmyra". Speaking to the Agence France- Presse news agency, he said: "Using the Roman theatre to execute people proves that these people are against humanity."
The Greco-Roman ruins at Palmyra are listed as a Unesco World Heritage Site, and the city's capture by ISIS prompted international concerns over the fate of its spectacular ancient treasures.
So far, it appears ISIS has not damaged the actual ruins, although it has blown up and desecrated Muslim graves in the city, and destroyed a statue outside the Palmyra Museum.
ISIS has regularly released videos of its mass executions with slick production and gruesome violence, which, experts say, is a key propaganda tool for the militant group.
Meanwhile, the United States-led coalition on Saturday and yesterday carried out some of its heaviest air strikes yet on the group's de facto Syrian capital, killing more than 30 people, including six civilians.
The strikes also damaged infrastructure in Raqa city, the group's bastion in northern Syria.
Elsewhere, regime forces backed by Lebanon's Hizbollah advanced on the last rebel-held town in the Qalamun region, near the Lebanese border. Fighting also continued between government troops and two rebel coalitions seeking to capture territory from the regime in northern Aleppo city.