ISIS killed 116 people it suspected of having collaborated with the Syrian government in Al-Qaryatain this month before it lost the area to government forces, a rights group said on Monday.

“IS has over a period of 20 days executed at least 116 civilians in reprisal killings, accusing them of collaboration with regime forces,” Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights monitor, said.

Al-Qaryatain was freed from ISIS terrorists on Saturday, three weeks after the terrorists seized control of it.

ISIS had captured the town in 2015 but lost it to a Russian-backed Syria forces last year.

“After the regime retook it (on Saturday), the town's residents found the bodies on the streets. They had been shot dead or executed with knives,” Abdel Rahman said.

“Most of the IS fighters who attacked the town a month ago were sleeper cells... They are from the town, know the town's residents and who is for or against the regime,” he said.

He added that the majority of those killed were executed in the last two days before ISIS lost the town again.

After the town was liberated, a resident said ISIS “monsters” killed over 100 people.

“These are people who don’t know God, they don’t know anything. They killed children and women with knives, they beat women, broke their arms,” he said.