The Syrian Observatory for Human Rights called it "the largest execution operation carried out by the Islamic State organization in 2017."
CNN cited a report by the Syrian Observatory for Human Rights which said the terror group carried out the mass killing in the the al-Mayadin desert near the strategic city of Deir Ezzor on Wednesday morning.
The monitoring group called it "the largest execution operation carried out by the Islamic State organization in 2017."
According to the report, the victims were between ages 18 and 25 and were "killed by sharp tools."
It was, however, not clear whether the victims were Syrian government forces, allied militia or rebel factions.
ISIS also reportedly killed at least 22 people in the Iraqi city of Tikrit, on Wednesday.
ISIS gunmen indiscriminately opened fire on police and civilians in the central Iraqi city before they blew themselves up, police officials told CNN.
No less than 31 other people were wounded in the attack, report said.
Tikrit, the birthplace of former Iraqi leader Saddam Hussein, was recaptured by Iraqi troops from ISIS in March 2015.