File Photo: US military vehicles on a patrol in the countryside near the town of Qamishli, Syria, Sunday, Dec. 4, 2022. AP
"A total of 61 civilians and seven soldiers have been killed in the attack," said Rami Abdel Rahman, who heads the Syrian Observatory for Human Rights.
The Britain-based Observatory, which has a wide network of sources inside Syria, said the attack had been carried out on Friday by jihadists on motorcycles who opened fire on truffle hunters.
The monitor said that IS was taking advantage of the annual harvest of the desert fungus delicacy, which generally runs from February to April, to carry out attacks in remote locations.
IS group did not immediately claim the attack on its usual channels.
Syrian state media had reported 53 deaths Friday, after the attack in the southwest town of Al-Sokhna.
It was the deadliest attack by IS since January last year when they stormed a prison in the Kurdish-controlled northeastern city of Hasakeh in a bid to free fellow jihadists.
The resulting fighting inside the city killed 105 people, mostly civilians, as well as 268 jihadists.
After the jihadists lost their last scraps of territory following a military onslaught backed by a US-led coalition in March 2019, IS remnants in Syria mostly retreated to hideouts in the desert.
They have since used such hideouts to ambush Kurdish-led forces and Syrian government troops while continuing to mount attacks in neighboring Iraq.