Over 10 Islamic State militants died after eating food poisoned by their cooks, who plotted the operation with the Free Syrian Army.
The incident that took place at the ISIS camp in Deir al-Zour also left at least over 20 ISIS fighters hospitalised.
According to the Times of Iraq the Syrian Free Army carried out an operation against the Islamic State with the help of Free Syrian Army operatives posing cooks at the ISIS camp that houses at least over 1,200 Islamic State militants.
The FSA, which ultimately wants to overthrow Syrian President Bashar Assad, has proved itself to be a strong opposing force for ISIS and recently it also launched a large campaign to clear several ISIS-held cities around Deir al-Zour.
Reports claim that the FSA for long has been working on an undercover operation 'for poisoning' the ISIS fighters. Initially, it had plotted to execute the plan in September during the Eid al-Adha, but was forced to reconsider due to unavoidable circumstances.
The cooks behind the plot have now left Deir al-Zour with their families with the help of the rebels, according to al-Arabiya.
The poisoning happened at Fath El-Sahel camp. The report, however, could not be independently verified. Incidentally, on social media platforms, the ISIS-affiliate accounts have neither accepted nor denied the incident.
A similar incident reportedly took place earlier in October in Iraq where four ISIS militants were poisoned to death by a local resident at a check point near al-Tajneed neighbourhood in Jalawla, 70km north-east of Baqubah.
The drastic step was taken by an Iraqi citizen, who offered poison-laced tea to the ISIS militants.