Syrian workers in Raqqa walk on a mass grave believed to contain the bodies of many hundreds of civilians (AP)

Syrian police discovered a mass grave in Palmyra, excavating 12 bodies in the ancient city that had been besieged by Islamic State group terrorists for two years, according to official media.

"Authorities found the remains of several civilians and soldiers in a mass grave near Palmyra's archeological theatre," Syria's official news agency SANA said.

SANA reported that twelve remains were retrieved and transferred to a hospital to be identified through DNA testing.

The terrorist group IS seized Palmyra twice between 2015 and 2017 when it launched campaigns to systematically destroy and loot the UNESCO world heritage site's monuments and temples.

The organization killed Palmyra's 82-year-old retired chief archaeologist Khaled al-Assaad after he refused to leave the city and utilized the ancient Roman theatre as a site for execution-style killings.

ISIS has claimed responsibility for 26,549 attacks in the past 5 years, most of which were focused on #Iraq.#Syria #Terrorism pic.twitter.com/u877l0CwCI
— Al Mayadeen English (@MayadeenEnglish) January 4, 2022

Mass graves are no stranger to the terrorist group which has committed all kinds of atrocities across Syria and any region they stepped in. They even blew up the tetrapylon monument and part of the Roman theatre in Palmyra before they were driven out by the Syrian Army in 2017.

Dozens of mass graves have been found in Iraq and Syria, but the identification process is slow, costly, and complicated.